ES2704830T3 - Air conditioner - Google Patents

Abstract

An air conditioner (1) comprising: a refrigerant circuit (10) including: at least one heat source unit (2) having a compressor (21) and a heat exchanger (23) on the side of the heat source, a utilization unit (4, 5) having an expansion mechanism (41, 51) on the utilization side and a heat exchanger (42, 52) on the utilization side, and a liquid refrigerant communication (6) and a gaseous refrigerant communication tube (7) for connecting the heat source unit to the utilization unit, the refrigerant circuit being capable of performing at least one refrigeration operation, in which the heat exchanger on the heat source side functions as a condenser of the compressed refrigerant in the compressor and the heat exchanger on the utilization side functions as an evaporator of the condensed refrigerant in the heat exchanger on the source side heat; and a shut-off valve (26) arranged in a position that is both downstream of the heat exchanger (23) on the heat source side and upstream of the liquid refrigerant communication pipe (6) in one direction flow rate of the refrigerant in the refrigerant circuit in the refrigeration operation, and configured to be able to close the refrigerant flow: characterized in that the air conditioner also comprises: a liquid surface detection sensor (39) provided in the heat exchanger on the heat source side, configured to detect the amount of liquid refrigerant accumulated in the heat exchanger on the heat source side, and arranged upstream of the shut-off valve (26) in the direction of the refrigerant flow in the refrigerant circuit in the refrigeration operation, and configured to perform the detection of the amount of liquid refrigerant located upstream of the check valve. closure by detecting a height of the liquid surface, in which the liquid surface is a boundary between the area where the refrigerant exists in a gaseous state and the area where the refrigerant exists in a liquid state, a memory (19 configured to store , in advance, data on the required amount of refrigerant that is required to properly perform an air conditioning operation using the refrigerant circuit, and a control unit (8) configured to perform the refrigeration operation with the valve closure (26) carded on the basis of a detection result of the liquid surface detection sensor (39) and the required amount of refrigerant.

Description

DESCRIPTION

Air conditioner

Technical field

The present invention relates to an air conditioner that performs an evaluation of whether the amount of refrigerant in a refrigerant circuit is adequate or not.

Previous technique

Conventionally, with respect to the amount of refrigerant in a refrigerant circuit of an air conditioner, the air conditioner is operated under specific conditions in order to evaluate whether or not an adequate amount of refrigerant is charged, which is in accordance with the size of the air conditioner, the length of a communication tube of the refrigerant circuit and the like. In the operation of the air conditioner under such specific conditions, an evaluation is made as to whether or not an appropriate quantity of refrigerant is charged, for example by detecting the degree of subcooling of condensed refrigerant in a condenser, while performing an operation in the control is carried out in such a way that the degree of superheating of the refrigerant evaporated in an evaporator reaches a predetermined value.

However, in such an operation, even if a predetermined degree of overheating has been reached, the pressure in each portion of the refrigerant circuit changes depending on factors such as the temperature of the indoor air exchanging heat with the refrigerant in a heat exchanger. on the utilization side, the temperature of the outside air as a heat source exchanging heat with the refrigerant in a heat exchanger on the side of the heat source, and the like which, as a consequence, changes the target value of the degree of Sub-cooling at the time of the evaluation of whether the amount of refrigerant is adequate or not. Therefore, it is difficult to improve the accuracy of the evaluation at the time of the evaluation of whether the amount of refrigerant is adequate or not.

With respect to this problem, according to the following Patent Document 1, the accuracy of the evaluation of the amount of refrigerant charged in a refrigerant circuit is improved by controlling the degree of overheating by an expansion mechanism on the side of the refrigerant. the use and control of the evaporation pressure by a compressor and detecting the degree of sub-cooling of the refrigerant at the outlet of a heat exchanger on the side of the heat source.

<Patent Document 1>

Japanese Patent Application No. 2004-173839.

Furthermore, document CA 2567304 A1 discloses an air conditioner comprising a heat source unit and a use unit interconnected through a refrigerant communication tube, in which it is accurately evaluated whether the refrigerant circuit is full with an adequate amount of refrigerant or not, in which the air conditioner can operate in a switchable manner or in a normal operating mode, in which the heat source unit, which has a compressor and a heat exchanger in the side of the heat source, is connected to units of use, which have expansion valves on the utilization side and heat exchangers on the utilization side through the refrigerant communication tube and each apparatus is controlled in function of the local load of the units of use, and a mode of operation of evaluation of the quantity of refrigerant, in which the units of use they align the refrigeration operation and the operating capacity of the compressor is controlled in such a way that the evaporation pressures of the heat exchangers on the utilization side are constant while controlling the expansion valves on the utilization side in such a way that the degree of overheating at the outlet of the heat exchangers on the utilization side is a positive value, and in the operation mode of the evaluation of the quantity of refrigerant, it is evaluated whether the refrigerant circuit is filled with an amount of refrigerant or not detecting the degree of over-cooling of the heat exchanger outlet orifice on the side of the heat source.

JP 2006-038453 A discloses a refrigeration unit and a method of detecting the amount of refrigerant in the refrigeration unit, in which the unit is provided with a main refrigerant circuit and a liquid level detection circuit , the refrigerant circuit including a compressor for compressing a gaseous refrigerant, a heat exchanger on the side of the heat source, the receiver for storing the liquid refrigerant, and a heat exchanger on the utilization side, wherein the liquid level detection circuit is provided to extract a part of the refrigerant in the receiver from the first prescribed position of the receiver, pressurizes it and the hot, and returns it to a suction side of the compressor after measuring a temperature of the refrigerant, and detects that the liquid level in the receiver reaches the first prescribed position.

Description of the invention

<Technical problem>

However, the evaluation of the amount of refrigerant according to the Patent Document 1 described above requires the control of the degree of superheating by the expansion mechanism on the utilization side and the control of the evaporation pressure by the compressor as the operating conditions to evaluate the amount of refrigerant and thus complicates. In addition, the error can become large due to factors such as a change in pressure on the condenser side due to a change in the condition of the outside air temperature, and it is difficult to stably maintain a constant operating state throughout moment, which is required as the operating conditions to properly assess the amount of refrigerant. The present invention is made in light of the problems described above, and an object of the present invention is to provide an air conditioner capable of simplifying the conditions required to assess whether the amount of refrigerant is adequate or not.

<Solution to the problem>

An air conditioner according to the present invention is defined by claim 1. The dependent claims refer to preferred embodiments.

An air conditioner according to an embodiment according to the present invention includes a refrigerant circuit, a shut-off valve, and a liquid surface sensing sensor as a refrigerant detection unit.

The refrigerant circuit includes a heat source unit having a compressor and a heat exchanger on the side of the heat source; a utilization unit having an expansion mechanism on the utilization side and a heat exchanger on the utilization side; and a liquid refrigerant communication tube and a gaseous refrigerant communication tube, which connects a heat source unit to a use unit. Furthermore, this refrigerant circuit is configured in such a way that at least one cooling operation can be carried out, in which the heat exchanger on the heat source side is caused to function as a condenser of the compressed refrigerant in the compressor and the heat exchanger on the utilization side is caused to function as an evaporator of condensed refrigerant in the heat exchanger on the side of the heat source. Here, as is evident, the refrigerant circuit may have a configuration capable of performing different operations than the cooling operation, such as a heating operation and the like. In addition, the shut-off valve is disposed in a position that is downstream of the heat exchanger on the heat source side and upstream of the liquid refrigerant communication tube in the flow direction of the refrigerant in the refrigerant circuit in the cooling operation, and is configured to be able to shut off the refrigerant flow. In addition, the refrigerant detection unit is disposed upstream of the shut-off valve in the direction of flow of the refrigerant in the refrigerant circuit in the refrigeration operation and is configured to perform detection of the liquid surface, this being the limit between the area where the refrigerant exists in a gaseous state and the area where the refrigerant exists in a liquid state. In this way, it detects a value of coolant that exists upstream of the shut-off valve. The detection includes here the detection of the amount of refrigerant itself, the detection to determine whether the amount of refrigerant is suitable or not and the like. It should be noted that the heat exchanger on the side of the heat source used here, which functions as a condenser of the refrigerant is not limited to the type that causes the refrigerant to be subjected to a gas-to-liquid phase change, but includes also a type that does not cause a phase change, but causes a change such as an increase in the density of the refrigerant as a result of heat exchange, such as in the case where carbon dioxide is used as the refrigerant, example. In addition, the use of the heat exchanger on the utilization side used here, which functions as a refrigerant evaporator is not limited to the type which causes the refrigerant to be subjected to a phase change from liquid to gas, but also includes a a type that does not cause a phase change, but causes a change such as a reduction in the density of the refrigerant as a result of heat exchange, such as in the case where carbon dioxide is used as the refrigerant, for example.

Here, during the cooling operation by the refrigerant circuit, when the shut-off valve disposed downstream of the heat exchanger on the side of the heat source is closed and the flow of refrigerant is closed, the liquid refrigerant, for example, which is condensed in the heat exchanger side of the heat source, which functions as an accumulator, will accumulate in the heat exchanger on the side of the heat source upstream of the shut-off valve, mainly because the circulation of refrigerant is stopped. At the same time, when the refrigeration operation is performed and the compressor is operated, a portion downstream of the shut-off valve and upstream of the compressor in the refrigerant circuit, which includes components such as the heat exchanger on the side of the compressor. utilization, the gaseous refrigerant communication tube, and the like, is depressurized and, consequently, refrigerant will hardly exist in that portion. Accordingly, the refrigerant in the refrigerant circuit is collected intensively upstream of the shut-off valve, and the refrigerant detection unit performs the detection of the amount of refrigerant that is collected intensively.

Accordingly, it is possible to simplify the conditions for carrying out an evaluation of the quantity of refrigerant and to evaluate whether the quantity of refrigerant is adequate or not.

The air conditioner includes a memory and a control unit. The memory stores, in advance, data on the required amount of refrigerant that is required to adequately perform an air conditioning operation using the refrigerant circuit. In addition, the control unit performs the cooling operation with the closing valve closed on the basis of a detection result of the refrigerant detection unit and the required amount of refrigerant.

Here, while the refrigeration operation is carried out, with the shut-off valve closed, the control unit compares the data on the required amount of refrigerant that are stored in the memory with the information relative to the amount of refrigerant accumulated upstream of the closing valve, which is evaluated by the refrigerant evaluation unit and in this way can automatically determine an excess or shortage of the refrigerant that exists in the refrigerant circuit.

According to some preferred embodiments, the shut-off valve is located at one end of the liquid refrigerant communication tube and the utilization side expansion mechanism is located at the other end of the liquid refrigerant communication tube. The control unit performs the control, in such a way that the temperature of the refrigerant flowing through the communication pipe of the liquid refrigerant reaches a constant value in the cooling operation, and then it closes the expansion mechanism of the utilization side and the Closing valve.

Here the control unit performs a control such that the temperature of the refrigerant that exists in the liquid refrigerant communication tube reaches a constant value, and then it closes one end and the other end of the liquid refrigerant communication tube to seal the tube tightly of liquid refrigerant communication. Accordingly, it is possible to accurately quantify the amount of refrigerant that exists in the liquid refrigerant communication tube. Then, when the control unit performs the cooling operation and drives the compressor, a portion from downstream of the compressor to the expansion mechanism of the utilization side in the refrigerant circuit will be depressurized and thus there will hardly be any refrigerant in that. portion, causing the refrigerant to accumulate upstream of the shut-off valve.

Accordingly, an exact amount of refrigerant is hermetically sealed in the liquid refrigerant communication tube and thus it is possible to reduce the number of portions in the refrigerant circuit where refrigerant hardly exists due to depressurization (portion where the evaluation error) and improve the accuracy of the evaluation.

In addition, for example, when the exact amount of refrigerant is hermetically sealed in the liquid refrigerant communication tube and in this way the amount of refrigerant that must accumulate upstream of the shut-off valve can be reduced by the amount in the tube. liquid refrigerant communication, it is possible to reduce the number of portions that must be detected by the refrigerant evaluation unit.

In addition, for example, when the refrigerant circuit is arranged in a building, even if the amount of refrigerant in the refrigerant circuit changes due to the arrangement of a very long liquid refrigerant communication tube, it is possible to seal the exact amount of refrigerant in the liquid refrigerant communication tube. In this way, when the refrigerant detection unit performs the detection of the amount of refrigerant upstream of the shut-off valve, the influence on detection due to the change can be reduced, allowing stable detection.

According to some preferred embodiments, the heat source unit includes a first heat source unit having a first compressor and a first heat exchanger of the heat source, and a second heat source unit having a second compressor and a second heat exchanger of the heat source. In addition, the shut-off valve includes a first shut-off valve disposed downstream of the first heat exchanger of the heat source in the flow direction of the coolant and capable of shutting off the coolant flow, and a second shut-off valve disposed downstream. of the second heat exchanger of the heat source in the refrigerant flow and capable of closing the flow of refrigerant. The refrigerant detecting unit includes a first refrigerant detection unit disposed upstream of the first shut-off valve in the refrigerant flow direction and configured to perform the detection of the amount of refrigerant existing upstream of the first refrigerant valve. closing in the flow direction of the refrigerant and configured to realize the detection of the amount of refrigerant that exists upstream of the second closing valve in the flow direction of the refrigerant. In addition, the memory stores in advance data on a first required quantity of refrigerant for the first heat source unit, and data on the second required amount of refrigerant for the second heat source unit. The control unit controls the operation of the first compressor on the basis of the first required amount of refrigerant and controls the operation of the second compressor on the basis of the second required amount of refrigerant.

Here, when the refrigerant circuit is provided with a plurality of heat source units, the control unit can control the compressor drive of each heat source unit in accordance with the amount of refrigerant required in the heat exchanger of the heat source of each heat source unit. Accordingly, the control unit can stop the actuation of the first compressor at a time when the first required quantity of refrigerant has accumulated in the first heat source unit, and can stop the operation of the second compressor at a time when the second amount Required refrigerant has been accumulated in the second heat source unit.

Accordingly, it is possible to control the operation of the compressor to adjust the amount of refrigerant, such that a specific amount of refrigerant accumulates in each heat source unit.

According to some preferred embodiments, the first heat source unit includes a first check valve disposed between the first compressor and the first heat exchanger of the heat source and is configured to stop the flow of refrigerant to the first compressor. In addition, the second heat source unit includes a second check valve disposed between the second compressor and the second heat exchanger of the heat source and configured to stop the flow of refrigerant to the second compressor.

Here, when the refrigerant circuit is provided with a plurality of heat source units, if, for example, the second compressor continues to be operated in a state in which the second required amount of refrigerant has not yet been reached in the second heat source unit, after the first reduced amount of refrigerant has accumulated in the first heat source unit, there is a risk that the refrigerant accumulated in the first heat source unit may flow backward.

With respect to this risk, here a check valve is arranged between the compressor and the heat exchanger of the heat source in each heat source unit.

Accordingly, it is possible to prevent the refrigerant temporarily accumulated in the heat source unit from flowing backwards.

<Effects of the present invention>

With the air conditioner according to the present invention it is possible to simplify the conditions to perform an evaluation with respect to the amount of refrigerant and to assess whether the amount of refrigerant is adequate or not.

It is possible to automatically determine an excess or shortage of the refrigerant that exists in the refrigerant circuit.

With the air conditioner according to some embodiments, an exact amount of refrigerant is hermetically sealed in the liquid refrigerant communication tube and in this way it is possible to reduce the number of portions in the refrigerant circuit where it is difficult to exist refrigerant due to depressurization (where the evaluation error occurs) and improve the accuracy of the evaluation.

With the air conditioner according to some embodiments, it is possible to control the operation of each compressor to adjust the amount of refrigerant, such that a specific amount of refrigerant accumulates in each heat source unit, when connected. a plurality of heat source units to the refrigerant circuit.

With the air conditioner according to some embodiments, it is possible to prevent the refrigerant temporarily accumulated in the heat source unit from flowing back after at least one of the plurality of connected heat source units has been stopped. .

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic configuration diagram of an air conditioner according to an embodiment of the present invention.

Figure 2 is a schematic view of an outdoor heat exchanger.

Figure 3 is a conceptual view showing the refrigerant accumulated in the outdoor heat exchanger. Figure 4 is a control block diagram of the air conditioner.

Figure 5 is a schematic view showing a state of the refrigerant flowing in a refrigerant circuit. Figure 6 is a flow diagram of a suitable refrigerant charging operation.

Figure 7 is a view showing how the refrigerant accumulates in the outdoor heat exchanger by closing an external expansion valve.

Fig. 8 is a schematic view showing a state of the refrigerant when the refrigerant is collected in the outdoor heat exchanger.

Figure 9 is a view showing another example of the outdoor heat exchanger.

Figure 10 is a schematic diagram of an air conditioner according to a second embodiment, in which a plurality of external heat exchangers are installed. Figure 11 is a schematic diagram of an air conditioner according to another embodiment.

Figure 12 is a schematic diagram of an air conditioner according to a third embodiment.

Figure 13 is a schematic view of the air conditioner according to a third embodiment when the indoor units are performing a cooling-cooling operation.

Fig. 14 is a schematic view of the air conditioner according to a third embodiment when the indoor units are performing a heating-heating operation.

Figure 15 is a schematic view of the air conditioner according to a third embodiment when the indoor units are performing a cooling-heating operation.

Figure 16 is a schematic view of the air conditioner according to a third embodiment when the indoor units are performing a heating-cooling operation.

Fig. 17 is a schematic view of the air conditioner according to a third embodiment when a constant control of the liquid temperature in an automatic refrigerant charging operation and an operation for evaluating the amount of refrigerant is performed.

Figure 18 is a schematic view of the air conditioner according to a third embodiment causes the liquid refrigerant to accumulate in the outdoor heat exchanger in the automatic refrigerant charging operation and the operation of evaluating the amount of refrigerant.

Fig. 19 is a schematic view of the air conditioner according to an alternative embodiment (A) of the third embodiment causing the liquid refrigerant to accumulate in the outdoor heat exchanger in the automatic refrigerant charging operation and the operation of evaluating the amount of refrigerant.

Fig. 20 is a schematic view of the air conditioner according to an alternative embodiment (B) of the third embodiment when the liquid refrigerant accumulates in the outdoor heat exchanger in the automatic refrigerant charging operation and the evaluation operation of the amount of refrigerant.

Description of the reference numbers

1 Air conditioner

2 Outdoor unit (heat source unit)

4, 5 Indoor unit (user unit)

6 Liquid refrigerant communication tube (refrigerant communication tube)

7 Gaseous refrigerant communication tube (refrigerant communication tube)

7d gaseous refrigerant communication tube discharged

7s gaseous refrigerant communication tube aspirated

10 Refrigerant circuit

21 Compressor

23 External heat exchanger (heat exchanger on the side of the heat source)

41, 51 Internal expansion valve (expansion mechanism on the utilization side)

42, 52 Interior heat exchanger (heat exchanger on the utilization side)

43, 53 Outdoor fan (blower)

69 Opening / closing valve

98 Reception unit

99 Valve opening / closing

400 Air conditioner

421 Second compressor

422 Three-step valve (switching means of branch communication)

424 Outside tube (coolant tube on the side of the heat source)

427 Bypass tube (bypass mechanism)

HPS Hot gas bypass circuit

SV4d Discharge gas opening / closing valve (first switching means)

SV4s Vacuum gas opening / closing valve (first switching means)

SV5d Discharge gas opening / closing valve (second switching means)

SV5s Vacuum gas opening / closing valve (second switching means)

BEST MODE FOR CARRYING OUT THE INVENTION

The following describes embodiments of an air conditioner according to the present invention.

(1) Configuration of the air conditioner

Figure 1 is a schematic configuration view of an air conditioner 1 according to an embodiment of the present invention. The air conditioner 1 is a device that is used to cool and heat a room in a building and the like by performing a cooling cycle operation of the compression type. The air conditioner 1 mainly includes an outdoor unit 2 as a heat source unit, indoor units 4 and 5 as a plurality (two in the present embodiment) of usage units connected in parallel to the outdoor unit 2, and a liquid refrigerant communication tube 6 and a gaseous refrigerant communication tube 7 as refrigerant communication tubes, which connect the outdoor unit 2 to the indoor units 4 and 5. In other words, a refrigerant circuit of the compression type 10 of the air conditioner 1 in the present embodiment is formed by the interconnection of the outdoor unit 2, the indoor units 4 and 5, and the liquid refrigerant communication tube 6 and the gaseous refrigerant communication tube 7 .

<Indoor unit>

The indoor units 4 and 5 are installed by means of incrustation or suspension from a roof of a room in a building or the like, or by means of mounting or the like on a wall surface of a room. The indoor units 4 and 5 are connected to the outdoor unit 2 through the refrigerant communication tube 6 and the gaseous refrigerant communication tube 7, and form part of the refrigerant circuit 10. The configurations of the interior units 4 and 5. It should be noted that because the indoor units 4 and 5 have the same configuration, only the configuration of the indoor unit 4 is described here, and with respect to the configuration of the indoor unit 5, reference numbers in the 50s instead of reference numbers in the 40s representing the respective portions of the indoor unit 4, and descriptions of those respective portions are omitted.

The indoor unit 4 mainly includes a coolant circuit on the inner side 10a (a coolant circuit 10b on the inner side in the case of the indoor unit 5) which forms a part of the coolant circuit 10. The coolant circuit in the inner side 10a mainly includes an inner expansion valve 41 as an expansion mechanism and an indoor heat exchanger 42 as a heat exchanger on the utilization side.

In the present embodiment, the inner expansion valve 41 is an electric expansion valve connected to the liquid side of the indoor heat exchanger 42 in order to adjust the flow rate or the like of the refrigerant flowing in the refrigerant circuit 10a on the inside.

In the present embodiment, the indoor heat exchanger 42 is a fin and tube type heat exchanger of the cross fin type formed by a heat transfer tube and numerous fins, and is a heat exchanger that functions as a refrigerant evaporator during a refrigeration operation to cool the room air and functions as a condenser of the refrigerant during a heating operation to heat the air in the room.

In the present embodiment, the indoor unit 4 includes an indoor fan 43 as a ventilation fan for introducing room air into the unit, causing the air to exchange heat with the refrigerant in the indoor heat exchanger 42 and then supply the air to the room as supply air. The indoor fan 43 is a fan capable of varying the flow rate of the air that is supplied to the indoor heat exchanger 42, and in the present embodiment, is a centrifugal fan, a fan of multiple blades or the like, which is driven by a 43m motor comprising a DC fan motor.

In addition, several types of sensors are arranged in the indoor unit 4. A temperature sensor 44 on the side of the liquid that senses the temperature of the refrigerant (i.e., the temperature of the refrigerant corresponding to the condensing temperature during the heating operation or the evaporation temperature during the cooling operation) is arranged on the liquid side of the indoor heat exchanger 42. A temperature sensor 45 on the side of the gas that senses the temperature of the refrigerant is arranged on the gas side of the exchanger of interior heat 42. A room temperature sensor 46 that senses the air temperature of the room that flows inside the unit (ie, the room temperature) is arranged on the air inlet side of the room of the indoor unit 4. In the present embodiment, the temperature sensor 44 on the liquid side, the temperature sensor 45 on the gas side, and the temperature sensor of room 46 comprise thermistors. In addition, the indoor unit 4 includes a control unit 47 on the interior side, which controls the operation of each portion forming the indoor unit 4. Additionally, the control unit 47 on the interior side includes a microcomputer for controlling the indoor unit 4, a memory and the like, and is configured in such a way that it can exchange control signals and the like with a remote controller (not shown) to individually drive the indoor unit 4 and can exchange control signals and the like with the outdoor unit 2 c through a transmission line 8a.

<Outdoor unit>

The outdoor unit 2 is installed outside a room of a building and the like, and is connected to the indoor units 4 and 5 through the liquid refrigerant communication tube 6 and the gaseous refrigerant communication tube 7, which form the circuit of refrigerant 10 with the indoor units 4 and 5.

The configuration of the outdoor unit 2 is described below. The outdoor unit 2 mainly includes a refrigerant circuit 10c on the outer side which forms a part of the refrigerant circuit 10. The refrigerant circuit 10c on the outdoor side mainly includes a compressor 21, a four-step switching valve 22, an outdoor heat exchanger 23 such as a heat exchanger on the heat source side, an outer expansion valve 38 as an expansion mechanism, an accumulator 24, a sub-unit refrigerator 25 as a temperature adjustment mechanism, a shut-off valve 26 on the liquid side, and a shut-off valve 27 on the gas side.

The compressor 21 is a compressor, whose operating capacity can be varied, and in the present embodiment is a compressor of the positive displacement type driven by a motor 21m, whose rotation speed is controlled by an inverter.

The four-step switching valve 22 is a valve for switching the direction of the flow of refrigerant, such that during the cooling operation, the four-step switching valve 22 is able to connect the discharge side of the compressor 21 to the gas side of the external heat exchanger 23 and connecting the suction side of the compressor 21 (specifically, the accumulator 24) to the gaseous refrigerant communication tube 7 (see the solid lines of the four-step switching valve 22 in the Figure 1) to cause the outdoor heat exchanger 23 to function as a condenser of the compressed refrigerant in the compressor 21 and to cause the indoor heat exchangers 42 and 52 to function as evaporators of the condensed refrigerant in the outdoor heat exchanger 23; and in such a way that, during the heating operation, the four-step switching valve 22 is able to connect the discharge side of the compressor 21 to the gaseous refrigerant communication tube 7 and connect the suction side of the compressor 21 to the side of gas from the outdoor heat exchanger 23 (see the dotted lines of the four-step switching valve 22 in Figure 1) to cause the indoor heat exchangers 42 and 52 to function as condensers of the compressed refrigerant in the compressor 21 and to cause the outdoor heat exchanger 23 to function as an evaporator of condensed refrigerant in the indoor heat exchangers 42 and 52.

In this embodiment, as shown in Figure 2, the outdoor heat exchanger 23 is, as it were, a fin and tube type heat exchanger, having a header 11, branching capillaries 12 and a plurality of flat tubes 13 connecting the header 11 to the branch capillaries 12, such that the branch capillaries 12 are arranged in a spaced apart manner and substantially parallel to each other. It should be noted that, as a heat exchanger in a refrigerant circuit to which the present invention is applied, it is not limited to such a fin and tube type heat exchanger. For example, it can be a shell-and-tube type heat exchanger, a plate-type heat exchanger, or the like (for example, see figure 9). The outdoor heat exchanger 23 is a heat exchanger that functions as a condenser that liquefies the gaseous refrigerant flowing in from the head 11 during the cooling operation and functions as an evaporator that evaporates the liquid refrigerant flowing in from the inside. the branching capillaries 12 during the heating operation, performing the heat exchange with the air supplied by the outdoor fan 28. The gas side of the outdoor heat exchanger 23 is connected to the compressor 21 and the four-way switching valve 22 , and the liquid side of the outdoor heat exchanger 23 is connected to the outer expansion valve 38 and the liquid refrigerant communication tube 6.

In addition, as shown in Figure 2 and Figure 3, a liquid surface sensing sensor 39 which detects the amount of condensed liquid refrigerant is provided on a side side of the outdoor heat exchanger 23. The detection sensor of the liquid surface 39 is a sensor for detecting the amount of liquid refrigerant accumulated in the outdoor heat exchanger 23 and formed by a tubular sensing member. Here, for example, as shown in FIG. 3, in the case of the cooling operation, in the outdoor heat exchanger 23, a high temperature gaseous refrigerant flowing in from the compressor 21 exchanges heat with the supplied air by the external fan 28 and, consequently, a sensible heat transfer occurs. As a result, the high temperature gaseous refrigerant is cooled to approximately the outside air temperature while maintaining its gaseous state. Then, the gaseous refrigerant exchanges more heat with the air supplied by the external fan 28 and, consequently, a latent heat transfer occurs. As a result, the gaseous refrigerant condenses, while maintaining its constant temperature, in a liquid refrigerant after passing through a two-phase gas-liquid state. The liquid surface detection sensor 39 detects the surface of the liquid, forming a boundary between the area, where the refrigerant exists in a gaseous state and the area, where the refrigerant exists in a liquid state as the liquid surface. It should be noted that, here, the liquid surface detection sensor 39 is not limited to the tubular sensing member described above. For example, it may be a sensor that senses the amount of liquid refrigerant accumulated in the outdoor heat exchanger 23, wherein the sensor includes thermistors arranged in a plurality of locations along the height direction of the outdoor heat exchanger 23, and detects the surface of the liquid, establishing a boundary between a superheated portion of the gaseous refrigerant, whose temperature is higher than the outside air temperature and a portion of the liquid refrigerant, whose temperature is substantially equal to the outside air temperature as the liquid surface, as described above.

In the present embodiment, the outer expansion valve 38 is an electric expansion valve connected to the liquid side of the outdoor heat exchanger 23 in order to adjust the pressure, flow rate, or the like of the refrigerant flowing in the refrigerant circuit 10c on the outer side, and the outer expansion valve 38 can be brought to a completely closed state.

In the present embodiment, the outdoor unit 2 includes the outdoor fan 28 as a ventilation blower to introduce the outside air into the unit, causing the air to exchange heat with the refrigerant in the outdoor heat exchanger 23 and then escape the air outside the room. The outdoor fan 28 is a fan capable of varying the flow rate of the air that is supplied to the outdoor heat exchanger 23, and in the present embodiment, is a propeller fan or the like driven by a motor 28m comprising a motor of DC fan.

The accumulator 24 is connected between the four-step switching valve 22 and the compressor 21 and is a container capable of accumulating the excess of refrigerant generated in the refrigerant circuit 10 in accordance with the change in the operating load of the indoor units 4 and 5 and the like.

In the present embodiment, the sub-cooler 25 is a double-tube heat exchanger, and is arranged to cool the coolant that must be sent to the interior expansion valves 41 and 51 after the refrigerant has been condensed into it. the outdoor heat exchanger 23. In the present embodiment, the sub-refrigerator 25 is connected between the outer expansion valve 38 and the shut-off valve 26 on the liquid side.

In the present embodiment, a bypass refrigerant circuit 61 is arranged as a cooling source of the sub-refrigerator 25. It should be noted that, in the above description, a portion corresponding to the refrigerant circuit 10, which excludes the bypass refrigerant circuit 61, referred to as a main refrigerant circuit for convenience.

The bypass refrigerant circuit 61 is connected to the main refrigerant circuit to cause a portion of the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 to branch out from the main refrigerant circuit and return to the of suction of the compressor 21. Specifically, the bypass refrigerant circuit 61 includes a branching circuit 64 connected to bypass a portion of the refrigerant sent from the outer expansion valve 38 to the inner expansion valves 41 and 51 at a position between the outer heat exchanger 23 and the sub-refrigerator 25, and a mixing circuit 65 connected to the suction side of the compressor 21 to return a portion of the refrigerant from the outlet in the bypass refrigerant circuit of the sub-refrigerator 25 to the suction side of the compressor 21. In addition, the bypass circuit n 64 is provided with a valve bypass expansion 62 for adjusting the flow rate of the refrigerant flowing in the bypass refrigerant circuit 61. Here, the bypass expansion valve 62 comprises an electrically operated expansion valve. Accordingly, the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 is cooled in the sub-refrigerator 25 by the refrigerant flowing to the bypass refrigerant circuit 61, which has been depressurized by the bypass expansion valve 62. In other words, the operation of the sub-cooler 25 is controlled by adjusting the degree of opening of the bypass expansion valve 62.

The shut-off valve 26 on the side of the liquid and the shut-off valve 27 on the gas side are valves arranged in connection holes to the equipment and the outer tubes (specifically, the liquid refrigerant communication tube 6 and the communication tube of gaseous refrigerant 7). The shut-off valve 26 on the liquid side is connected to the outdoor heat exchanger 23. The shut-off valve 27 on the gas side is connected to the four-step switching valve 22.

In addition, several sensors other than the liquid surface detection sensor 39 described above are provided in the outdoor unit 2. Specifically, an aspiration pressure sensor 29 which senses the compressor suction pressure is provided in the outdoor unit 2. 21, a discharge pressure sensor 30 that senses the discharge pressure of the compressor 21, a suction temperature sensor 31 that detects the suction temperature of the compressor 21, and a discharge temperature sensor 32 that senses the compressor discharge temperature 21. The suction temperature sensor 31 is disposed in a position between the accumulator 24 and the compressor 21. A temperature sensor of the heat exchanger 33 which senses the temperature of the refrigerant flowing through the External heat exchanger 23 (ie, the temperature of the refrigerant that corresponds to the hard condensing temperature The cooling operation or the evaporation temperature during the heating operation is arranged in the outdoor heat exchanger 23. A temperature sensor on the liquid side 34 which detects a coolant temperature Tco is arranged on the liquid side of the external heat exchanger 23. A temperature sensor of the liquid tube 35 which senses the temperature of the refrigerant (i.e., the temperature of the liquid tube) is disposed at the outlet on the side of the main refrigerant circuit of the sub-refrigerator 25. The mixing circuit 65 of the bypass refrigerant circuit 61 is provided with a bypass temperature sensor 63 for detecting the temperature of the refrigerant flowing from the outlet in the bypass refrigerant circuit of the sub-refrigerator 25. A sensor of outside temperature 36 which senses the temperature of the outside air flowing inside the unit (ie, at outside temperature) is disposed on the side of the outside air inlet in unit 2. In the present embodiment, the suction temperature sensor 31, the discharge temperature sensor 32, the temperature sensor 33 of the heat exchanger, the temperature sensor on the liquid side 34, the temperature sensor of the liquid tube 35, the outdoor temperature sensor 36, and the bypass temperature sensor 63 comprise thermistors. In addition, the outdoor unit 2 includes an outdoor side control unit 37 which controls the operation of each portion forming the outdoor unit 2. In addition, the outdoor side control unit 37 includes a microcomputer for controlling the outdoor unit 2, a memory, an inverter circuit that controls the motor 21m, and the like, and is configured in such a way that it can exchange control signals and the like with the control units of the inner side 47 and 57 of the indoor units 4 and 5 through the transmission line 8a. In other words, a control unit 8 that performs control of the operation of the entire air conditioner 1 is formed by the control units of the inner side 47 and 57, the control unit of the outer side 37, and the line of transmission 8a interconnecting control units 37, 47 and 57.

As shown in Figure 4, the control unit 8 is connected to be able to receive sensor detection signals 29 to 36, 39, 44 to 46, 54 to 56, and 63 and also to be able to control various equipment and valves 21, 22, 24, 28m, 38, 41, 43m, 51, 53m, and 62 on the basis of these detection signals and the like. It should be noted that, as shown in Figure 4, the control unit 8 has a memory 19 connected to it, and reads data stored in the memory 19 when it performs several controls. Here, the data stored in the memory 19 includes, for example, data on the appropriate amount of refrigerant in the refrigerant circuit 10 of the air conditioner 1 in each building, which is determined taking into account the length of the tube and the like after that the air conditioner 1 is installed in the building. As described below, the control unit 8 reads the data when performing an automatic refrigerant charge operation and a refrigerant leak detection operation to charge only a suitable amount of refrigerant in the refrigerant circuit 10. In addition, the memory 19 stores data on the determined amount of refrigerant in the liquid tube (determined amount of refrigerant in the liquid tube Y) and data on the amount of refrigerant collected in the external heat exchanger (amount of refrigerant collected in the exchanger external heat X) in addition to the data on the appropriate amount of refrigerant (adequate amount of refrigerant Z) and the following relationship is fulfilled: Z = XY). Here, the determined amount of refrigerant in the liquid tube Y is the amount of refrigerant held in a portion from a downstream part of the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 through the outer expansion valve 38, the sub-cooler 25, and the liquid refrigerant communication tube 6 and a portion from a branching portion below the outer expansion valve 38 to the bypass expansion valve 62 when these portions are sealed in operation described below by the liquid refrigerant, whose temperature is constant (it should be noted that the refrigerant circuit 10 is designed in such a way that the capacity of a portion from the expansion valve is reduced external 38 to sub-refrigerator 25, thus reducing the influence on the evaluation error). In addition, the amount of refrigerant collected in the outdoor heat exchanger X is the amount of refrigerant that is obtained by subtracting the determined amount of refrigerant in the liquid tube Y from the amount of suitable refrigerant Z. In addition, the memory 19 stores an expression from which the amount of refrigerant accumulated in a portion from the outer expansion valve 38 to the outdoor heat exchanger 23 can be calculated on the basis of the data on the liquid surface of the outdoor heat exchanger 23.

In addition, the control unit 8 has an alarm screen 9 connected thereto, which is formed by LEDs and the like and which indicates that a refrigerant leak is detected in the refrigerant leak detection operation (described below). Here, Figure 4 is a control block diagram of the air conditioner 1.

<Refrigerant communication tube>

The refrigerant communication tubes 6 and 7 are refrigerant tubes that are arranged on the side when the air conditioner 1 is installed at an installation site, such as a building. Like the refrigerant communication tubes 6 and 7, pipes having various lengths and diameters are used according to the conditions of the installation, such as an installation site, combination of an outdoor unit and an indoor unit, and the like. Accordingly, for example, when an air conditioner is newly installed, it is necessary to charge an adequate amount of refrigerant in the air conditioner 1 according to the conditions of the installation, such as lengths, diameters and the like of the communication tubes. of coolant 6 and 7.

As described above, the refrigerant circuit 10 of the air conditioner 1 is formed by the interconnection of the refrigerant circuits on the inner side 10a and 10b, the refrigerant circuit on the outer side 10c, and the communication tubes of refrigerant 6 and 7. Additionally, the control unit 8 formed by the control units 47 and 57 on the inner side and the control unit 37 on the outer side allows the air conditioner 1 in the present embodiment to switch and operate between the cooling operation and the heating operation by the four-step switching valve 22 and controlling each equipment of the outdoor unit 2 and the indoor units 4 and 5 according to the operating load of each of the indoor units 4 and 5.

(2) Operation of the air conditioner

Next, the operation of the air conditioner 1 in the present embodiment is described.

The modes of operation of the air conditioner 1 in the present embodiment include: normal operating mode where the control of the constituent equipment of the outdoor unit 2 and of the indoor units 4 and 5 is carried out in accordance with the operating load of each of the indoor units 4 and 5; a mode of operation of automatically charging the appropriate amount of refrigerant, wherein an adequate amount of refrigerant is charged into the refrigerant circuit 10 when a test operation is performed after installation or the like of the constituent equipment of the air conditioner 1; and a refrigerant leak detection mode of operation, where the presence of a refrigerant leak from the refrigerant circuit 10 is evaluated after said test operation has been completed and normal operation has begun.

The operation in each mode of operation of the air conditioner 1 is described below.

<Normal operation mode>

(Refrigeration operation)

First, the cooling operation in the normal operation mode is described with reference to FIGS. 1 and 3.

During the cooling operation, the four-step switching valve 22 is in the state represented by the solid lines in FIG. 1, that is, a state in which the discharge side of the compressor 21 is connected to the side of the external heat exchanger 23 and also the suction side of the compressor 21 is connected to the gas sides of the heat exchangers in terrors 42 and 52 through the gas-side shut-off valve 27 and the refrigerant communication tube gaseous 7. Here, the outer expansion valve 38 and the bypass expansion valve 62 are in a fully open state, and the closing valve 26 on the liquid side and the closing valve 27 on the gas side are also in an open state. open state.

When the compressor 21, the outdoor fan 28, the indoor fans 43 and 53 are started in this state of the refrigerant circuit 10, a gaseous refrigerant is sucked off at low pressure in the compressor 21 and is compressed in a high-pressure gas refrigerant. Pressure. Subsequently, the high pressure gaseous refrigerant is sent to the outdoor heat exchanger 23 through the four-step switching valve 22, exchanges heat with the outside air supplied by the outdoor fan 28 and condenses in a high pressure liquid refrigerant. . Then, this high-pressure liquid refrigerant passes through the outer expansion valve 38, flows into the sub-cooler 25, exchanges heat with the refrigerant flowing into the refrigerant circuit of the refrigerant. bypass 61, it is further cooled and becomes sub-cooled. At this time, a portion of the high pressure liquid refrigerant condensed in the outdoor heat exchanger 23 branches off into the branch coolant circuit 61 and is depressurized by the bypass expansion valve 62. Subsequently, it is returned to the suction side of the compressor 21. Here, the refrigerant passing through the bypass expansion valve 62 is depressurized to near the suction pressure of the compressor 21 and thus a portion of the refrigerant is evaporated. Then, the refrigerant flowing from the outlet of the bypass expansion valve 62 of the bypass refrigerant circuit 61 to the suction side of the compressor 21 passes through the sub refrigerator 25 and exchanges heat with the high pressure liquid refrigerant sent from the heat exchanger 23 on the side of the main refrigerant circuit to the indoor units 4 and 5.

Then, the high-pressure liquid refrigerant that has been subcooled is sent to the indoor units 4 and 5 through the shut-off valve 26 on the liquid side and the liquid refrigerant communication tube 6.

The high pressure liquid refrigerant sent to the indoor units 4 and 5 is depressurized close to the suction pressure of the compressor 21 by the indoor expansion valves 41 and 51, it becomes cooled in a low gas-liquid two phase state pressure, is sent to the indoor heat exchangers 42 and 52, exchanges heat with the room air in the indoor heat exchangers 42 and 52, and evaporates in a gaseous refrigerant at low pressure.

This gaseous low pressure refrigerant is sent to the outdoor unit 2 through the gaseous refrigerant communication tube 7 and flows into the accumulator 24 through the shut-off valve 27 on the gas side and the four-way switching valve 22. Then, the low pressure gaseous refrigerant that has flowed into the accumulator 24 is sucked back into the compressor 21.

Here, as for the distribution state of the refrigerant in the refrigerant circuit 10 during the refrigeration operation, the refrigerant in each of the liquid state, two-phase gas-liquid state, and gaseous state is distributed as shown in the figure 5. Specifically, provided that an area between a portion upstream of the outer expansion valve 38 and a downstream portion of the outdoor heat exchanger 23 is taken as a base point, a portion from the base point to upstream of the interior expansion valves 41 and 51 including the sub-cooler 25 and the liquid refrigerant communication tube 6 of the main refrigerant circuit, and a portion from the base point to upstream of the bypass expansion valve 62 they are filled with the refrigerant in liquid state. A portion from the interior expansion valves 41 and 51 to the middle portion of the indoor heat exchangers 42 and 52, a portion from the bypass expansion valve 62 to downstream of the bypass refrigerant circuit 61 connected to the sub-refrigerator 25, and a portion corresponding to a middle part (upstream of the liquid portion) of the outdoor heat exchanger 23 are filled with the refrigerant in a two-phase gas-liquid state. In addition, other portions in the refrigerant circuit 10 are filled with the gaseous refrigerant. Specifically, provided that a part upstream of each of the interior heat exchangers 42 and 52 is taken as a base point and provided a part upstream of the sub-cooler 25, to which the refrigerant circuit is connected. of branch 61, take as a further base point, a portion from these base points to a part upstream of the outdoor heat exchanger 23, including the gaseous refrigerant communication tube 7 in the main refrigerant circuit, a part course downstream of the bypass refrigerant circuit 61, the accumulator 24, and the compressor 21 is carried with the gaseous refrigerant.

It should be noted that although the refrigerant is distributed in the refrigerant circuit 10 in the manner described above during a normal refrigeration operation, the refrigerant is distributed in such a way that the liquid refrigerant is collected in the liquid refrigerant communication tube 6 and the outdoor heat exchanger 23 during a refrigeration operation in an automatic loading operation of the appropriate amount and the refrigerant leak detection operation (described below).

(Heating operation)

The heating operation in the normal operating mode is described below.

During the heating operation, the four-step switching valve 22 is in a state represented by the dotted lines in Figure 1, ie, a state in which the discharge side of the compressor 21 is connected to the sides of gas from the internal heat exchangers 42 and 52 through the shut-off valve 27 on the gas side and the gaseous refrigerant communication tube 7 and also the suction side of the compressor 21 is connected to the gas side of the exchanger of outer heat 23. The degree of opening of the outer expansion valve 38 is adjusted to be able to depressurize the refrigerant flowing inside the outdoor heat exchanger 23 to a pressure where the refrigerant can evaporate (i.e. evaporation pressure). ) in the external heat exchanger 23, In addition, the shut-off valve 26 on the liquid side and the shut-off valve 27 on the gas side are in an open state. The degree of opening of each of the inner expansion valves 41 and 51 is adjusted in such a way that the degree of sub-cooling of the refrigerant becomes constant at the outlet of each of the indoor heat exchangers 42 and 52. In the present embodiment, the degree of sub-cooling of the refrigerant at the outlet of each of the indoor heat exchangers 42 and 52. is detected by converting the discharge pressure of the compressor 21 detected by the sensor of the discharge pressure 30 at the saturated temperature corresponding to the condensation temperature, and subtracting the temperature of the refrigerant detected by the temperature sensors 44 and 54 on the respective liquid side from this saturated coolant temperature. In addition, the bypass expansion valve 62 is closed. When the compressor 21, the outdoor fan 28, the indoor fans 43 and 53 are turned on in this state of the refrigerant circuit 10, the low pressure gaseous refrigerant is sucked in. the compressor 21 is compressed in a high pressure gaseous refrigerant, and is sent to the indoor units 4 and 5 through the four-step switching valve 22, the shut-off valve 27 on the gas side 7 and the pipe of gaseous refrigerant communication.

Then, the high pressure gaseous refrigerant sent to the indoor units 4 and 5 exchanges heat with the room air in the respective indoor heat exchangers 42 and 52 and is condensed in a high pressure liquid refrigerant. Subsequently, the high pressure gaseous refrigerant is depressurized according to the degree of opening of the inner expansion valves 41 and 51 as it passes through the interior expansion valves 41 and 51.

The refrigerant that has passed through the internal expansion valves 41 and 51 is sent to the outdoor unit 2 through the liquid refrigerant communication tube 6, is also depressurized through the shut-off valve 26 on the side of the liquid, the sub-cooler 25 and the outer expansion valve 38 and then flows into the outdoor heat exchanger 23. Then, the refrigerant in the two-phase low pressure gas-liquid state which has flowed into the exchanger of external heat 23 exchanges heat with the outside air supplied by the external fan 28, evaporates in a gaseous refrigerant at low pressure and flows into the accumulator 24 through the four-step switching valve 22. Then, the gaseous refrigerant at low pressure that has flowed in the accumulator 24 is sucked back into the compressor 21.

Such operation control as described above in the normal operation mode is performed by the control unit 8 (more specifically, the control units 47 and 57 on the inner side, the control unit 37 on the outer side and the transmission line 8a connecting between control units 37, 47 and 57) that function as control means of normal operation to perform normal operation including refrigeration operation and heating operation.

<Operating mode of automatic charging of the proper refrigerant quantity>

Here, the operation mode of automatic loading of the proper amount of refrigerant is described.

The mode of operation of automatic charging of the proper amount of refrigerant is an operation mode that is performed at the time of the test operation after installation or the like of the constituent equipment of the air conditioner 1. In this mode, it is charged automatically a suitable amount of refrigerant according to the capacities of the liquid refrigerant communication tube 6 and the gaseous refrigerant communication tube 7 to the refrigerant circuit 10.

First, the shut-off valve 26 on the liquid side and the shut-off valve 27 of the outdoor unit 2 are opened and the refrigerant circuit 10 is filled with the refrigerant which is blown in the outdoor unit 2 in advance.

Next, an operator performing the proper refrigerant automatic charging operation connects a refrigerant cylinder 15 for additional charging to an electromagnetic charge valve 17 of the refrigerant circuit 10. In this way, the refrigerant cylinder 15 is adjusted to a state that communicates with the suction side of the compressor 21 through a charging tube 16 and, consequently, a state is achieved in which the refrigerant can be charged in the refrigerant circuit 10. The electromagnetic charging valve 17 it is configured to be able to control the amount of charge from the refrigerant cylinder 15 when the electromagnetic charging valve 17 is connected it is connected to the control unit 37 on the outer side and the degree of opening of its valve is controlled. In the step of connecting the refrigerant cylinder 15 to the electromagnetic charging valve 17, the electromagnetic charging valve 17 is in a closed state.

It should be noted that a charging point in the refrigerant circuit is not limited to the above. For example, a service hole capable of charging refrigerant from the vicinity of the shut-off valve 27 on the gas side may be arranged at the time of charging. Furthermore, the electromagnetic charging valve 17 used here can be configured in two ways: either only capable of opening and closing as an electromagnetic valve or else capable of adjusting the flow rate like a magnetic valve.

Then, when an operator issues a command to start the operation of automatically charging the proper amount of refrigerant to the control unit 8 directly or using a remote controller (not shown) or the like, the control unit 8 starts the process from the step S11 to step S17 shown in figure 6. Here, figure 6 is a flow diagram of the automatic loading operation of the appropriate refrigerant amount. Next, each stage is described in the order.

In step S11, the control unit 8 fully opens the charging electromagnetic valve 17 when the connection of the refrigerant cylinder 15 to the charging electromagnetic valve 17 is completed.

In step S12, the control unit 8 performs the same operation as the cooling operation in the normal operation mode described above. Specifically, a state is reached where the four-step switching valve 22 of the outdoor unit 2 is as indicated by the solid lines in Fig. 1 and the indoor expansion valves 41 and 51 of the indoor units 4 and 5 and the expansion valve 38 are open and in that state, the compressor 21, the outdoor fan 28 and the indoor fans 43 and 53 are started, and the cooling operation is performed in both the indoor units 4 and 5 in a forced manner. this way, the refrigerant contained in the refrigerant cylinder 15 is progressively charged into the refrigerant circuit 10 through the charging electromagnetic valve 17 and the charging tube 16.

Furthermore, in step S12, the control unit 8 performs both the cooling operation described above and a constant control of the liquid temperature at the same time. In the constant control of the temperature of the liquid, a control of the condensation pressure and a control of the temperature of the liquid tube are carried out. In the control of the condensing pressure, the flow rate of the external air supplied by the outdoor fan 28 to the outdoor heat exchanger 23 is controlled in such a way that the condensing pressure of the refrigerant in the outdoor heat exchanger 23 becomes constant . Because the condensing pressure of the condenser in the condenser changes greatly due to the effect of the outside temperature, the flow rate of the indoor air supplied from the outdoor fan 28 to the outdoor heat exchanger 23 is controlled by the motor 28m . Accordingly, the condensing pressure of the refrigerant in the heat exchanger 23 becomes constant, and the state of the refrigerant flowing through the condenser will be stabilized. Accordingly, a state is achieved in which a high pressure liquid refrigerant flows in the flow path from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 including the outdoor expansion valve 38, the side of the main refrigerant circuit of the sub-cooler 25 and the liquid refrigerant communication tube 6 and the flow path from the outdoor heat exchanger 23 to the bypass expansion valve 62 of the bypass refrigerant circuit 61. In this way , the pressure of the refrigerant is also stabilized in a portion from the outdoor heat exchanger 23 to the inner expansion valves 41 and 51 and to the bypass expansion valve 62, and the portion is sealed by the cooling liquid, resulting in this way a stable state. It should be noted that, in the control of the condensation pressure, the discharge pressure of the compressor 21 is used, which is detected by the discharge pressure sensor 30 or the temperature of the refrigerant flowing through the outdoor heat exchanger 23 which is detected by the heat exchange temperature sensor 33.

In controlling the temperature of the liquid pipe, the operation of the sub-cooler 25 is controlled in such a way that the temperature of the coolant sent from the sub-cooler 25 to the inner expansion valves 41 and 51 becomes constant. Accordingly, the density of the refrigerant in the refrigerant tubes can be stabilized from the sub-refrigerator 25 to the inner expansion valves 41 and 51, including the liquid refrigerant communication tube 6. Here, the performance of the sub-cooler 25 for increasing or reducing the flow rate of the refrigerant flowing in the bypass refrigerant circuit 61, such that the temperature of the refrigerant detected by the temperature sensor of the liquid tube 35 becomes constant. Accordingly, the amount of heat exchange between the refrigerant flowing on the side of the main refrigerant circuit of the sub-refrigerator 25 and the refrigerant flowing on the side of the bypass refrigerant circuit is adjusted. It should be noted that the flow rate of the refrigerant flowing in the refrigerant flowing in the bypass refrigerant circuit 61 increases or decreases as the control unit 8 adjusts the degree of opening of the bypass expansion valve. 62

In step S13, the control unit 8 evaluates whether the temperature of the liquid has become constant or not by the constant control of the temperature of the liquid in step S12 above. Here, if it is judged that the temperature of the liquid is constant, the process goes to step S14. On the other hand, if it is judged that the temperature of the liquid has not become constant, the process returns to step S12 to continue the constant control of the temperature of the liquid.

When the temperature of the liquid is controlled to be constant by the constant control of the temperature of the liquid, the portion of liquid in the refrigerant circuit 10, which is indicated by the black zone in FIG. 5, is stably sealed by the liquid refrigerant, whose temperature is constant. The black zone specifically includes: a portion from a downstream part of the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 through the outdoor expansion valve 38, the sub-refrigerator 25, and the water pipe. communication of liquid refrigerant 6, and a portion from a branching portion downstream of the outer expansion valve 38 to the bypass expansion valve 62. Accordingly, a state is achieved where the cooling operation of the refrigerant circuit 10 is carried out in a stable manner while the quantity of the refrigerant corresponding to a value of the amount of refrigerant Y determined by the liquid tube recorded in the memory 19 is always kept in the black zone shown in figure 5.

In step S14, because it has been determined that the temperature of the liquid is constant, the control unit 8 closes the inner expansion valves 41 and 51, the bypass expansion valve, and the outer expansion valve 38 therein. order. Accordingly, it is possible to stop the circulation of refrigerant, keeping the amount of refrigerant that corresponds to the amount of refrigerant Y determined by the liquid tube, and accumulate the refrigerant, whose quantity is exactly equal to the amount of refrigerant Y determined by the liquid tube in the portion described above. It should be noted that the compressor 21 and the external fan 28 they continue to work even after each expansion valve closes. According to it. As shown in Figure 8, the portion from the inner expansion valves 41 and 51 to the suction side of the compressor 21 is depressurized and, consequently, it will be difficult for refrigerant to exist in the indoor heat exchangers 42 and 52, in the gaseous refrigerant communication tube 7 and in the accumulator 24. Further, as shown in Fig. 8, the refrigerant discharged from the discharge side of the compressor 21 exchanges heat in the outdoor heat exchanger 23 with the outside air sent from the outdoor fan 28; the refrigerant in the gaseous state liquefies; and the liquid refrigerant accumulates from the top of the outer expansion valve 38 to the outdoor heat exchanger 23 (see Figure 7).

Here, when the outdoor fan 28 starts to rotate, the outdoor heat exchanger 23 continuously exchanges heat with the outside air sent from the outdoor fan 28. Therefore, first, in the outdoor heat exchanger 23, a gaseous refrigerant to high temperature, which flows there from the compressor 21, exchanges heat with the outside air and, consequently, the high temperature gaseous refrigerant is cooled to approximately the temperature of the outside air, while maintaining its gaseous state (heat transfer) sensitive). Then the gaseous refrigerant exchanges more heat with the outside air and, therefore, condenses the gaseous refrigerant, while maintaining its constant temperature, in a liquid refrigerant after passing through a two-phase gas-liquid state (transfer of gas). latent heat). In addition, because the refrigerant circulation is stopped, currently, as shown in FIG. 7, the refrigerant in the liquid state accumulates in the portion from upstream of the outer expansion valve 38 to the lower portion of the heat exchanger. exterior 23.

In step S15, the control unit 8 detects the liquid surface of the refrigerant accumulated in the outdoor heat exchanger 23 by the liquid surface detection sensor 39. Here, the liquid surface detection sensor 39 detects the surface of the liquid refrigerant, setting a boundary between the area where the temperature does not change due to the latent heat transfer described above and the area where the temperature changes due to the sensible heat transfer described above as the liquid surface of the liquid refrigerant . Accordingly, the control unit 8 replaces the height h of the surface of the liquid obtained by the detection sensor of the liquid surface 39 (see Figure 7) in an expression recorded in the memory 19 and thus calculates the amount of refrigerant accumulated in the portion from the outer expansion valve 38 to the outdoor heat exchanger 23.

In step S16, the control unit 8 evaluates whether the amount of refrigerant calculated in the previous step S15 has reached a value of the amount of refrigerant X collected in the external heat exchange according to the data recorded in the memory 19. Here, when the amount of refrigerant has not reached the amount of refrigerant X collected in the external heat exchange, the process returns to step S14 to continue charging refrigerant in the refrigerant circuit 10. On the other hand, when it is evaluated that the amount of refrigerant has reached the amount of refrigerant X collected in the external heat exchange, the process goes to step S17.

In step S17, the control unit 8 evaluates that a suitable amount of refrigerant has been charged in the refrigerant circuit 10, and closes the charging electromagnetic valve 17 in order to stop the charging of refrigerant from the refrigerant cylinder 15. to the refrigerant cylinder 10. Accordingly, the amount of suitable refrigerant Z, which is the sum of the amount of refrigerant Y determined by the liquid tube and the amount of refrigerant X collected in the external heat exchange, is charging in the refrigerant circuit 10. Then, the charging electromagnetic valve 17 is closed, the refrigerant cylinder 15 is removed and the automatic charging operation of the appropriate refrigerant quantity is completed.

<Refrigerant leakage detection operation mode>

The operation mode for detecting the refrigerant leak is described below.

The mode of operation for detecting the refrigerant leak is substantially the same as the operation of automatically charging the appropriate amount of refrigerant, so that only the differences are described.

In the present embodiment, the refrigerant leak detection operation mode is an operation that is performed, for example, periodically (for a period of time such as a vacation or in the middle of the night when no air conditioning is needed). or similar), to detect whether the refrigerant in the refrigerant circuit 10 leaks or does not leak out due to an unforeseen factor.

In the operation for detecting the refrigerant leak, the process of the flow diagram described above is performed for the operation of automatic change of the appropriate refrigerant quantity, except for step S11 and step S17.

Specifically, the control unit 8 performs the cooling operation and the constant control of the temperature of the liquid in the refrigerant circuit 10, and closes the inner expansion valves 41 and 51, the bypass expansion valve 62, and the valve of external expansion 38 when the temperature of the liquid becomes constant to determine the amount of refrigerant Y determined by the liquid tube. Then, the unit control 8 accumulates the liquid refrigerant in the outdoor heat exchanger 23 continuing the cooling operation.

Here, when the height h of the liquid surface detected by the sensing sensor of the liquid surface 39 remains the same for a given period of time, the control unit 8 replaces the height h of the liquid surface at that instant in an expression recorded in the memory 19 and in this way calculates an amount of liquid refrigerant X 'evaluated accumulated in the portion from the outer expansion valve 38 to the outdoor heat exchanger 23. Here, the presence of a refrigerant leak from the refrigerant circuit 10 is evaluated by adding the amount of refrigerant Y determined by the liquid tube to the amount of liquid refrigerant X 'evaluated to be calculated and determining whether the sum reaches or not the amount of suitable refrigerant Z.

It should be noted that the operation of the compressor 21 stops rapidly after the height h of the liquid surface remains the same for a predetermined period of time and the data on the height h of the liquid surface is obtained.

In addition, a method for evaluating refrigerant leak detection is not limited to the method described above, in which the amount of liquid refrigerant X 'evaluated is calculated. The leak detection can be carried out, for example, by calculating a standard height H of the liquid surface in advance, which corresponds to the optimum amount of refrigerant and recording the value in the memory 19 and thus directly comparing the height h of liquid detected with the standard height H of the liquid surface, which serves as an index, without the need to calculate the quantity of liquid refrigerant X 'evaluated as described.

(3) Characteristics of the air conditioner

The air conditioner 1 in this embodiment has the following characteristics.

(TO)

In the air conditioner 1 in this embodiment, the flow of refrigerant is closed by the outer expansion valve 38 when the cooling operation is performed and, consequently, the liquid refrigerant is accumulated in the outdoor heat exchanger 23 which It works as a condenser of the refrigerant. Then, the amount of refrigerant can be maintained in the amount of refrigerant Y determined by the liquid tube by sealing the portion from the outer expansion valve 38 to the inner expansion valves 41 and 51 and to the bypass expansion valve 62 through the liquid refrigerant that has a predetermined temperature making constant control of the temperature of the liquid. On the other hand, when the compressor 21 is driven in the cooling operation, the density of the refrigerant in other portions in the refrigerant circuit 10 will be extremely low and hardly any refrigerant will be present.

Accordingly, simply by constantly monitoring the temperature of the liquid, it is possible to charge an adequate amount of refrigerant in the refrigerant circuit 10 and determine an excess or shortage of the amount of refrigerant to detect a refrigerant leak, simplifying the At the same time carrying out an evaluation regarding the amount of refrigerant.

For example, the need for conventional control types, such as pressure control on the suction side of the compressor 21 in the refrigerant circuit 10 to be constant, is eliminated. Accordingly, it is possible to expand the conditions for performing the automatic refrigerant charging operation and the refrigerant leak detection operation, compared to conventional conditions. In addition, because the indoor heat exchangers 42 and 52 are not driven, but only depressurized, there is no risk of the indoor units 4 and 5 freezing when the automatic refrigerant charging operation and the operation of the refrigerant is performed. detection of refrigerant leak.

(B)

In the air conditioner 1 in this embodiment, there will be no refrigerant not only in the indoor heat exchangers 42 and 52 and in the liquid refrigerant communication tube 7, but also in the accumulator 24, closing the interior expansion valves 41 and 52 and by the bypass expansion valve 62, while the operation of the compressor 21 continues.

Accordingly, it is difficult for refrigerant to accumulate in the accumulator 24, independently of the outside air temperature. Therefore, it is possible to effectively reduce error in the detection of the amount of refrigerant. (4) Second embodiment

The refrigerant circuit formed by the interconnection of the refrigerant circuits on the inner side 10a and 10b, the refrigerant circuit on the outer side 10c, and the refrigerant communication tubes 6 and 7 and including an outdoor unit is an example of the refrigerant circuit 10 of the air conditioner 1 in the first embodiment described above.

However, the present invention is not limited thereto. For example, the refrigerant circuit may have a configuration, in which a plurality of outdoor units are arranged in parallel, as in an air conditioner of a second embodiment described below.

Specifically, for example, as shown in Figure 10, an air conditioner 200 having two heat source units, ie, the outdoor unit 2 and the outdoor unit 3, is described as an example.

<Indoor unit>

The indoor units 4 and 5 have the same configurations as those shown in the first embodiment described above and, therefore, their descriptions are omitted.

<Outdoor unit>

The outdoor units 2 and 3 are installed outside a building and the like, and are connected in parallel to the indoor units 4 and 5 through the liquid refrigerant communication tube 6 and the gaseous refrigerant communication tube 7, form the circuit of refrigerant 10 with the indoor units 4 and 5.

It should be noted that the configuration of the outdoor unit 2 is the same as in the first embodiment described above and, therefore, its description is omitted.

The configuration of the outdoor unit 3 is described below. The outdoor unit 3 mainly includes an external side coolant circuit 10d which forms a part of the coolant circuit 10. The outer side coolant circuit 10d mainly includes a compressor 71, a valve four-step switching device 72, an outdoor heat exchanger 73 such as a heat exchanger on the heat source side, an outdoor expansion valve 88 as an expansion mechanism, an accumulator 74, a sub-refrigerator 75 as a temperature adjustment mechanism, a shut-off valve 76 on the liquid side and a shut-off valve on the gas side 77.

The compressor 71 is a compressor, whose capacity can be varied and in the present embodiment is a compressor of the positive displacement type driven by a motor 71m, whose rotation speed is controlled by an inverter.

The four-way switching valve 72 is a valve for switching the direction of the refrigerant flow such that, during the cooling operation, the four-way switching valve 72 is able to connect the discharge side of the compressor 71 to the gas side of the external heat exchanger 73, while the suction side of the compressor 71 (specifically, the accumulator 74) is connected to the gaseous refrigerant communication tube 7 (see the solid lines of the four-way switching valve 22 in Fig. 10) to cause the outdoor heat exchanger 73 to function as a condenser of the compressed refrigerant in the compressor 71 and to cause the external heat exchangers 42 and 52 to function as evaporators of the condensed refrigerant in the outdoor heat exchanger 73 and such that, during the heating operation, the four-step switching valve 72 is capable of c connecting the discharge side of the compressor 71 to the gaseous refrigerant communication tube 7, while connecting the suction side of the compressor 71 to the gas side of the outdoor heat exchanger 73 (see the dotted lines of the four-way switching valve 72 in Figure 10) to cause the indoor heat exchangers 42 and 52 to function as condensers of the compressed refrigerant in the compressor 71 and cause the outdoor heat exchanger 73 to function as an evaporator of the condensed refrigerant in the indoor heat exchangers 42 and 52.

It should be noted that, like the outdoor heat exchanger 23 shown in Figure 2, the outdoor heat exchanger 73 in the second embodiment is called the fin and tube type exchanger having a header, branching capillaries and flat tubes . It should be noted that with respect to the heat exchanger in the refrigerant circuit of the second embodiment to which the present invention is applied, it is not limited to such a fin and tube type heat exchanger. For example, it may be a shell and tube type heat exchanger, a plate type heat exchanger, or the like (for example, see Figure 9). In addition, a liquid surface sensing sensor 89 that detects the amount of condensed coolant is also provided on a side side of the outer heat exchanger 73. The liquid surface sensing sensor 89 is a sensor for detecting the amount of liquid refrigerant accumulated in the outdoor heat exchanger 73, and formed by a tubular sensing member. As in the case of the first embodiment, the liquid surface detection sensor 89 detects a boundary between the area where the liquid refrigerant exists in a gaseous state and the area where the refrigerant exists in a liquid state such as the surface of liquid. It should be noted that here, the liquid surface detection sensor 89 can be, for example, a sensor that detects the quantity of liquid refrigerant accumulated in the outdoor heat exchanger 73, in which the sensor includes thermistors arranged in a plurality of locations along the direction of the height of the outdoor heat exchanger 73 and detects a boundary between a superheated portion of the gaseous refrigerant, whose temperature is higher than the outside air temperature and a portion of the liquid refrigerant, whose temperature is substantially equal to the temperature of the outside air that the liquid surface.

In the present embodiment, the outer expansion valve 88 is an electric expansion valve connected to the liquid side of the outdoor heat exchanger 73 in order to adjust the pressure, flow rate, or the like of the refrigerant flowing in the refrigerant circuit 10d on the outer side, and the outer expansion valve 88 can be brought to a completely closed state.

In the present embodiment, the outdoor unit 3 includes an outdoor fan 78 as a ventilation fan to introduce the outside air into the unit and discharge the air to the outside after the heat exchange with the refrigerant in the outdoor heat exchanger 73. The outdoor fan 78 is a fan capable of varying the flow rate of the air that is supplied to the outdoor heat exchanger 73, and in the present embodiment is a fan of propellers or the like driven by a motor 78m comprising a DC fan motor.

The accumulator 74 is connected between the four-way switching valve 72 and the compressor 71, and is a container capable of accumulating the excessive refrigerant generated in the refrigerant circuit 10 in accordance with the change in the operating load of the indoor units 4 and 5 and the like.

In the present embodiment, the sub-cooler 75 is a double-tube heat exchanger, and is arranged to cool the refrigerant to be sent to the interior expansion valves 41 and 51 after the refrigerant is condensed in the exchanger of external heat 73. In the present embodiment, the sub-cooler 75 is connected between the outer expansion valve 88 and the shut-off valve 76 on the liquid side.

In the present embodiment, a bypass refrigerant circuit 91 is arranged as a cooling source of the sub-refrigerator 75. It should be noted that, in the following description, a portion corresponding to the refrigerant circuit 10, excluding the circuit of bypass refrigerant 91, is referred to as a main refrigerant circuit for convenience.

The bypass refrigerant circuit 91 is connected to the main refrigerant circuit to branch a portion of the refrigerant sent from the heat exchanger 73 to the inner expansion valves 41 and 51 from the main refrigerant circuit and to return the branched refrigerant to the suction side of the compressor 71. Specifically, the bypass refrigerant circuit 71 includes a branching circuit 94 connected to branch a portion of the refrigerant sent from the outer expansion valve 88 to the inner expansion valves 41 and 51 in a position between the outdoor heat exchanger 73 and the sub-refrigerator 75, and a mixing circuit 95 connected to the suction side of the compressor 71 to return a portion of the refrigerant from the outlet on the side of the bypass coolant circuit of the sub-cooler 75 to the suction side of the compressor 71. Ade further, the branching circuit 94 is provided with a bypass expansion valve 92 for adjusting the flow rate of the refrigerant flowing in the bypass refrigerant circuit 91. Here, the bypass expansion valve 92 comprises an expansion valve electrically operated. Accordingly, the refrigerant sent from the outdoor heat exchanger 73 to the indoor expansion valves 41 and 51 is cooled in the sub-refrigerator 75 by the refrigerant flowing in the bypass refrigerant circuit 91, which has been depressurized by the bypass expansion valve 92. In other words, the performance of the sub-cooler 75 is controlled by adjusting the degree of opening of the bypass expansion valve 92.

The shut-off valve 76 on the side of the liquid and the shut-off valve 77 on the gas side are valves arranged in connection holes to the external equipment and to the tubes (specifically, a liquid refrigerant communication tube 6d and a communication tube of gaseous refrigerant 7f). The shut-off valve 76 on the liquid side is connected to the outdoor heat exchanger 73. The shut-off valve 77 on the gas side is connected to the four-way switching valve 72.

In addition, several sensors other than the liquid surface sensing sensor 89 described above are provided in the outdoor unit 3. Specifically, an aspiration pressure sensor 79 which detects the compressor suction pressure is provided in the outdoor unit 3. 71, a discharge pressure sensor 80 that senses the discharge pressure of the compressor 71, a suction temperature sensor 81 that senses the suction pressure of the compressor 71, and a discharge temperature sensor 82 that detects the discharge temperature of the compressor 71. The suction temperature sensor 81 is disposed in a position between the accumulator 74 and the compressor 71. A temperature sensor 83 of the heat exchanger which senses the temperature of the refrigerant flowing through the exchanger of external heat 73 (that is, the temperature of the refrigerant corresponding to the condensation temperature during the refrigeration operation or the evaporation temperature during the heating operation) is arranged in the outdoor heat exchanger 73. A temperature sensor 84 on the side of the liquid which senses a temperature of the refrigerant is arranged on the liquid side of the heat exchanger. outer heat 73. A temperature sensor 85 that senses the side of the refrigerant circuit (i.e., the temperature of the liquid tube) is disposed at the outlet on the side of the main refrigerant circuit of sub-refrigerator 75. The circuit of Mixture 95 of bypass refrigerant circuit 91 is provided with a bypass temperature sensor 93 to detect the temperature of the refrigerant flowing from the outlet on the side of the bypass refrigerant circuit of sub-refrigerator 75. A temperature sensor exterior 86 that senses the temperature of the outside air that flows inside the unit (it is say, the outside temperature) is disposed on the outside air inlet side of the outdoor unit 3. In the present embodiment, the suction temperature sensor 81, the discharge temperature sensor 82, the temperature sensor of the Heat exchanger 83, temperature sensor 84 on the liquid side, temperature sensor 85 of the liquid jet, outdoor temperature sensor 86, and tap temperature sensor 93 comprise thermistors. In addition, the outdoor unit 3 includes an outdoor side control unit 87 that controls the operation of each portion forming the outdoor unit 3. Additionally, the outdoor side control unit 87 includes a microcomputer for controlling the outdoor unit 3, a memory, and an inverter circuit that controls the 71m motor. Like the outdoor side control unit 37, the outdoor side control unit 87 is configured in such a way that it can exchange control signals and the like with the indoor side control units 47 and 57 of the indoor units 4 and 5 through the transmission line 8a. In other words, the control unit 8 which controls the operation of the entire air conditioner 1 is formed by the control units of the inner side 47 and 57, the control unit of the outer side 37, the control unit on the outer side 87, and the transmission line 8a interconnecting the control units 37, 47 and 57.

It should be noted that the control unit 8 has the memory 19 connected to it and reads data recorded in the memory 19 when several controls are performed. Here, the data stored in the memory 19 includes, for example, data on the appropriate amount of refrigerant in the refrigerant circuit 10 of the air conditioner 1 in each building, which is determined taking into account the length of the tube and the like after that the air conditioner 1 is installed in the building. As described below, the control unit 8 reads this data when the automatic refrigerant charging operation and the refrigerant leak detection operation is performed to charge only a suitable amount of refrigerant to the refrigerant circuit 10. In addition, the memory 19 stores data on the amount of refrigerant Y determined by the liquid tube, a first quantity of refrigerant X1 collected in the external heat exchange and a second quantity of refrigerant X2 collected in the external heat exchange, in addition to the data on the amount of refrigerant suitable Z and the following ratio is fulfilled: Z = X1 X2 Y. Here, the amount of refrigerant Y determined by the liquid tube is the data on the amount of refrigerant when the following portions are sealed by the liquid refrigerant , whose temperature is constant in the refrigeration operation described below: at the same time a part of the course ab garlic of the external heat exchanger 23 and the first liquid refrigerant communication tube 6c; a portion corresponding to a downstream part of the outdoor heat exchanger 73 and the second liquid refrigerant communication tube 6d; a portion from a mixing portion where the first liquid refrigerant communication tube 6c and the second liquid refrigerant communication tube 6d are mixed together to the inner expansion valves 41 and 51 through the first liquid refrigerant communication tube 6c ; and a portion from a branching portion downstream of the outer expansion valve 38 to the branch expansion valve 62; and a portion from the branch valve downstream of the outer expansion valve 88 to the bypass expansion valve 92 (it should be noted that the portion from the outer expansion valve 38 to the sub-refrigerator 25 is designed to have low capacity, so it has little influence on the evaluation error). In addition, the first quantity of external heat exchange refrigerant X1 and the second quantity of external heat exchange refrigerant X2 are the quantities divided proportionally according to the capacity of each of the external units 2 and 3 starting from the quantity of refrigerant obtained by subtracting the quantity of refrigerant Y determined by the liquid tube from the amount of refrigerant Z suitable. In addition, the memory 19 stores an expression between the liquid surface of the outdoor heat exchanger 23 and the amount of refrigerant accumulated in the portion from the outdoor expansion valve 38 to the outdoor heat exchanger 23 in the operation described below. In addition, the memory 19 stores an expression between the liquid surface of the outdoor heat exchanger 73 and the amount of refrigerant accumulated in the portion from the outdoor expansion valve 88 to the outdoor heat exchanger 73 in the operation described below.

In addition, the control unit 8 has the alarm screen 9 connected thereto, which is formed by LEDs and the like and which indicates that a refrigerant leak is detected in the refrigerant leak detection operation (described below).

<Refrigerant communication tube>

The refrigerant communication tubes 6 and 7 are refrigerant tubes that are arranged in place when the air conditioner 1 is installed at the site of the installation, such as a building. Like the refrigerant communication tubes 6 and 7, tubes having various lengths and diameters are used according to the conditions of the installation, such as an installation location, combination of an outdoor unit and an indoor unit, and the like. Accordingly, for example, when a new air conditioner is installed, it is necessary to charge an adequate amount of refrigerant to the air conditioner 1 according to the installation conditions, such as lengths, diameters, and the like of the communication tubes of the air conditioner. refrigerant 6 and 7.

As described above, the refrigerant circuit 10 of the air conditioner 1 is formed by the interconnection of the refrigerant circuits 10a and 10b of the interior side, the refrigerant circuits 10c and 10d of the exterior side and the refrigerant communication pipes. 6 and 7. Here, the outdoor air coolant circuit 10c and the outdoor air coolant circuit 10d are connected in parallel to the coolant communication pipes 6 and 7. The outdoor air coolant circuit 10c is connected through of the first liquid refrigerant communication tube 6c and a first gaseous refrigerant communication tube 7c, and the circuit of external air refrigerant 10d is connected through the second liquid refrigerant communication tube 6d and the second gaseous refrigerant communication tube 7f. Additionally, the control unit 8 formed by the control units of the inner side 47 and 57 and the control units of the outer side 37 and 87 allows the air conditioner 1 in the present embodiment to switch and perform the cooling operation and the heating operation by the four-step switching valves 22 and 72 and controlling each equipment of the outdoor units 2 and 3 and the indoor units 4 and 5 according to the operating load of each of the indoor units 4 and 5 .

<Operation of air conditioner>

It should be noted that the modes of operation of the air conditioner 200 in the second embodiment include: the normal mode of operation, in which the control of the constituent equipment of the outdoor units 2 and 3 and of the indoor units 4 and 5 it is carried out in accordance with the operating load of each of the indoor units 4 and 5; the automatic loading operation mode of the appropriate amount of refrigerant, in which an adequate amount of refrigerant is charged to the refrigerant circuit 10 when a test operation is performed after installation or the like of constituent equipment of the air conditioner. ; and the operation mode for detecting the refrigerant leak, wherein the presence of refrigerant leakage is evaluated from the refrigerant circuit 10 after such a test operation has ended and normal operation has begun.

Here, the normal mode of operation is the same as in the first embodiment described above and, therefore, its description is omitted.

<Automatic loading operation mode of the proper amount of refrigerant>

The operation of automatically charging the right amount of refrigerant in the second embodiment is the same as in the first embodiment from the stage of realization of the constant control of the temperature of the liquid to close the inner expansion valves 41 and 51, the branch expansion valves 62 and 92, and the outer expansion valves 38 and 88 are that order. It should be noted that here the refrigerant cylinder 15 is connected to each of the charging electromagnetic valves 17 and 17 'and is adjusted to a state which communicates with the suction side of each of the compressors 21 and 71 through of the charging tubes 16 and 16 'and, accordingly, a reaches a state in which the refrigerant can be charged to the refrigerant circuits 10c and 10d.

Unlike the first embodiment, in the second embodiment, after the step described above, the cooling operation is continued in each of the outdoor units 2 and 3 to accumulate an amount of liquid refrigerant (X1) corresponding to the capacity of the outdoor unit 2 and an amount of liquid refrigerant (X2) corresponding to the capacity of the outdoor unit 3 in the outdoor heat exchanger 23 and the outdoor heat exchanger 73, respectively. At this time, the control unit 8 evaluates using the detection sensor of the liquid surface 39, whether or not the required amount of refrigerant (first quantity of external heat exchange refrigerant X1) has accumulated in the heat exchanger. outer 23 and also evaluates separately, using the liquid surface detection sensor 89, whether or not the required amount of refrigerant (second quantity of external heat exchange refrigerant X2) has accumulated in the outdoor heat exchanger 73. Then the control unit 8 stops one of the compressors 21 and 71, respectively, provided for the outdoor units 2 and 3, in which the accumulation of the respective amount of refrigerant in its external heat exchangers has first been detected. and 73. Here, as shown in Fig. 10, a check valve 69 to prevent the refrigerant from flowing back to the compressor 21 is provided between the compressor 21 and the external heat exchanger 23, and a check valve 99 to prevent the refrigerant from flowing back to the compressor 21 is provided between the compressor 71 and the heat exchanger and the heat exchanger 73. both, even when any one of the external heat exchangers 23 and 73 is filled with the required amount of refrigerant that is held there and one of the corresponding compressors 21 and 71 is stopped, the other of the operating compressors 21 and 71 will not cause that the refrigerant kept there flows back. When it is judged that the required amount of refrigerant has accumulated in the other outdoor heat exchanger, the control unit 8 closes the electromagnetic charging valve 17, stops the operation of the compressor corresponding to the other outdoor heat exchanger, removes the cylinder of refrigerant 15 and the operation of automatically charging the appropriate amount of refrigerant ends in order to stop charging refrigerant from the refrigerant cylinder 15 to the refrigerant circuit 10.

<Refrigerant leak detection mode of operation>

The operation mode for detecting refrigerant leaks is described below.

The operation mode for detecting the refrigerant leak is substantially the same as the automatic loading operation of the appropriate amount of refrigerant, so that only the differences are described.

In the refrigerant leak detection operation in the second embodiment, the process of automatic loading operation of the appropriate amount of refrigerant is performed, except the process of fixing the refrigerant cylinder 15 and the like.

Specifically, the control unit 8 performs the cooling operation and the constant control of the temperature of the liquid in the refrigerant circuit 10, closes the inner expansion valves 41 and 51, the bypass expansion valves 62 and 92 and the valves of external expansion 38 and 88 when the liquid temperature becomes constant, and determines the amount of liquid refrigerant Y determined in the liquid tube. Then, continuing the cooling operation, the control unit 8 accumulates the liquid refrigerant in each of the external heat exchangers 23 and the external heat exchangers 73.

Here, with respect to the first quantity of liquid refrigerant X1 collected in the external heat exchange when the height h of the liquid surface detected by the detection sensor 39 of the liquid surface remains the same for a predetermined period of time, the control unit 8 replaces the height h of the surface of the liquid at this time in an expression recorded in the memory 19 and thus calculates a first quantity of liquid refrigerant X1 'evaluated accumulated in the portion from the external expansion valve 38 to the external heat exchanger 23. Further, with respect to the second quantity of liquid refrigerant X2 collected in the external heat exchange, when the height h of the liquid surface detected by the detection sensor 89 of the liquid surface remains the same for a predetermined period of time, the control unit 8 replaces the height h of the liquid surface at this time it is in an expression recorded in the memory 19 and in this way calculates a second quantity of liquid refrigerant X2 'evaluated accumulated in the portion from the outer expansion valve 88 to the outdoor heat exchanger 73.

Here, the presence of a refrigerant leakage from the refrigerant circuit 10 is evaluated by adding the amount of refrigerant Y determined in the liquid tube to the first quantity of liquid refrigerant X1 'evaluated and the second quantity of liquid refrigerant X2' evaluated. with calculated and it is determined whether the sum is equal or not to the amount of refrigerant Z suitable.

It should be noted that the operation of the compressors 21 and 71 stops quickly after the height h of the liquid surface remains the same for a predetermined period of time and the data on the height h of the liquid surface is obtained. In this way, the operation for detecting the refrigerant leak is terminated.

(5) Characteristics of the second embodiment

In addition, in the air conditioner 200 having a plurality of external units 2 and 3, it is possible to collect the amount of accumulated refrigerant X1 of heat exchange in the external heat exchange 23 and the second quantity of refrigerant X2 collected in the exchange of external heat in the outdoor heat exchanger 73 and perform the operation to separately anneal a suitable amount of refrigerant in each of them. (6) Third realization

<Configuration of the air conditioner in the third embodiment>

Figure 12 shows a schematic refrigerant circuit 410 of an air conditioner 400 according to another embodiment of the present invention.

The air conditioner 400 is a device that is used to cool and heat the air in a building and the like by performing a refrigeration cycle operation of the vapor compression type.

The air conditioner 400 mainly includes an outdoor unit 402, a plurality (two in the present embodiment) of indoor units 404 and 405, connection units 406 and 407, the outdoor unit 402, the liquid refrigerant communication tube 6 , a gaseous refrigerant communication tube discharged 7d, and a gaseous refrigerant communication tube sucked 7s. The air conditioner 400 is configured to be able to perform the simultaneous cooling and heating operation according to the needs of each air-conditioning space in the building where the indoor units 404 and 405 are installed, for example, as in the case of carrying out the cooling operation in an air-conditioning space, while performing the heating operation of a different air-conditioning space and the like.

In the refrigerant circuit 410 of the air conditioner 400 in this embodiment, the interior expansion valve 41 of the indoor unit 404 is connected to the outdoor heat exchanger 23 of the outdoor unit 402 through the refrigerant communication tubes liquid 6 and 464. In addition, the inner expansion valve 51 of the indoor unit 405 is connected to the outdoor heat exchanger 23 of the outdoor unit 402 through the liquid refrigerant communication tubes 6 and 465. The interior expansion valve 41 of the indoor unit 404 and the indoor expansion valve 51 of the indoor unit 405 are connected to the outdoor heat exchanger 23. In addition, the indoor heat exchanger 42 of the indoor unit 404 is connected to the connecting unit 406 through of a gaseous refrigerant connection tube 74ds, and the indoor heat exchanger 52 of the indoor unit 405 is connected to the connection unit 407 through a connecting tube of gaseous refrigerant 75ds. In addition, the connection unit 406 is connected to the compressor 21 of the outdoor unit 402 via the discharged gaseous refrigerant communication tubes 7d and 74d; the connecting unit 407 is connected to the compressor 21 of the outdoor unit 402 via the discharged gaseous refrigerant communication tubes 7d and 75d; the connecting unit 406 is connected to the compressor 21 of the outdoor unit 402 through the gaseous refrigerant communication tubes sucked 7s and 74s; and the connecting unit 407 is connected to the compressor 21 of the outdoor unit 402 through the gaseous refrigerant communication tubes sucked 7s and 75s. It should be noted that the compressor 21 and the outdoor heat exchanger 23 are connected to each other through an outer tube 424. The refrigerant circuit 410 of the air conditioner 400 is configured in the manner described above.

<Outdoor unit>

The outdoor units 404 and 405 are installed by means of embedding or suspension from a ceiling in a building and the like or by means of mounting or the like on a wall surface in a building. The indoor units 404 and 405 are connected to the outdoor unit 402 via the refrigerant communication tubes 6, 7d and 7s and the connection units 406 and 407, and form part of the refrigerant circuit 10.

The configurations of the indoor units 404 and 405 are described below. It should be noted that, since the indoor units 404 and 405 have the same configuration, only the configuration of the indoor unit 404 is described here and the portion descriptions are omitted. respective in the configuration of the indoor unit 405.

The indoor unit 404 mainly includes the inner expansion valve 41, the indoor heat exchanger 42, and the inner tube 444 which connects the inner expansion valve 41 to the indoor heat exchanger 42. In the present embodiment, the Inner expansion 41 is an electric expansion valve connected to a side of inner tube 444 of inner heat exchanger 42 in order to adjust the flow rate or the like of the refrigerant. In the present embodiment, the indoor heat exchanger 42 is a fin-tube type heat exchanger, of the cross fin type, formed by a heat transfer tube and numerous fins, and performs heat exchange between the coolant and indoor air. The indoor unit 404 includes the indoor fan 43 and the indoor fan motor 43m and can draw the indoor air into the unit, cause heat exchange between the indoor air and the refrigerant flowing through the indoor heat exchanger 42, and Then supply the air as supply air to the interior space.

In addition, several sensors are provided in the outdoor unit 404. A temperature sensor on the liquid side (not shown) which senses the temperature of the liquid refrigerant is arranged on the liquid side of the indoor heat exchanger 42, and a sensor temperature on the gas side (not shown), which detects the temperature of the gaseous refrigerant is arranged on the gas side of the indoor heat exchanger 42. In addition, the indoor unit 404 has a suction temperature sensor RA (not shown) which detects the indoor air temperature sucked into the unit.

In addition, the indoor unit 404 includes the indoor side control unit 47 which controls the degree of opening of the inner expansion valve 41, the speed of rotation of the motor 43m of the indoor fan, and other operations. Although the illustration is omitted, the control unit 47 on the inner side is connected to each sensor, the inner expansion valve 41, the motor 43m of the indoor fan and the like via a communication line, and can control each of they. The control unit 47 on the inner side forms a part of the control unit 8 of the air conditioner 400 and includes a microcomputer for controlling the indoor unit 404 and a memory. The control unit 47 on the inner side is configured in such a way that it can exchange control signals and the like with a remote controller (not shown) and can exchange control signals and the like with the outdoor unit 402. As mentioned above, the configurations of the components forming the indoor unit 405, such as the interior expansion valve 51, the indoor heat exchanger 52, an interior pipe 454, the indoor fan 53, the indoor fan motor 53m, and the control unit 57 on the inner side are the same as the respective components described above, which form the indoor unit 404.

<Outdoor unit>

The outdoor unit 402 is installed on the roof of a building and the like, and is connected to each of the indoor units 404 and 405 through the connection units 406 and 407 and the refrigerant communication pipes 6, 7d and 7s .

Next, the configuration of the outdoor unit 402 is described.

The outdoor unit 402 includes mainly: the compressor 21, the motor 21m, the outdoor heat exchanger 23, the outdoor fan 28, the motor 28m of the outdoor fan, the sub-refrigerator 25, a sub-cooling circuit 474, a valve sub-cooling expansion 472, outer tube 424, low pressure outer tube 425, high pressure outer tube 426, bypass tube 427, four-step switching valve 22, three-way valve 422 , the external expansion valve 38, an external high-pressure valve SV2b, the accumulator 24, the sensor for detecting the liquid surface 39, the electromagnetic charging valve 17 for the charging of refrigerant by the refrigerant cylinder 15 (described below), the charging tube 16, the shut-off valve 26 on the liquid side, a high-pressure shut-off valve 27d on the gas side, and sensors such as a low pressure shutoff valve 27s on the gas side, the temperature sensor of the liquid tube 35, and the like.

It should be noted that the structure in the vicinity of the outdoor heat exchanger 23 and the liquid surface detection sensor 39 is the same as in the first embodiment, and the position relationship is as shown in Figure 2 .

The compressor 21 is a compressor of the positive displacement type, whose operating capacity can be varied by the control unit 37 on the outer side through inverter control, and the operating capacity can be varied by controlling the rotation frequency of the inverter. 21 engine

The outdoor heat exchanger 23 is a heat exchanger capable of functioning as an evaporator and a condenser of the refrigerant, and is a fin and tube type heat exchanger of the cross fin type which exchanges heat with the refrigerant using air as the source of heat. The side of the outer tube 424 (gas side) of the outdoor heat exchanger 23 is connected to the four-step switching valve 22 and its liquid side is connected to the shut-off valve 26 on the liquid side.

The sub-refrigerator 25 is a triple tube heat exchanger and is arranged to cool the refrigerant to be sent to the indoor expansion valves 41 and 51 after the refrigerant has condensed in the outdoor heat exchanger 23. The sub -cooler 25 is connected between the outer expansion valve 38 and the shut-off valve 26 on the liquid side.

In this embodiment, the sub-cooling circuit 474 is arranged as a cooling source of the sub-cooler 25. It should be noted that, in the following description, a portion corresponding to the refrigerant circuit 10, excluding the Sub-cooling 474 is referred to as a main refrigerant circuit for convenience.

The sub-cooling circuit 474 is connected to the main refrigerant circuit to cause a portion of the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 to branch off from the main refrigerant circuit and return to the of suction of the compressor 21. Specifically, the sub-cooling circuit 474 includes a branching portion connected to branch a portion of the refrigerant sent from the outer expansion valve 38 to the inner expansion valves 41 and 51 at a position between the exchanger of external heat 23 and the sub-cooler 25 and a mixing portion connected to the suction side of the compressor 21 to return a portion of the refrigerant from the outlet on the side of the bypass refrigerant circuit of the sub-cooler 25 to the suction of the compressor 21. In addition, the bypass portion is di The sub-cooling expansion valve 472 is used to adjust the flow rate of the refrigerant flowing in the sub-cooling circuit 474. Here, the sub-cooling expansion valve 472 comprises an electrically operated expansion valve. Accordingly, the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51 is cooled in the sub-refrigerator 25 by the refrigerant flowing in the sub-cooling circuit 474 which has been depressurized by the sub-cooling expansion valve 472. In other words, the operation of the sub-cooler 25 is controlled by adjusting the opening degree of the sub-cooling expansion valve 472.

The outdoor unit 402 includes the outdoor fan 28 and the motor 28m of the outdoor fan and can suck the outside air into the unit, cause heat exchange between the outside air and the refrigerant flowing through the outdoor heat exchanger 23, and then expel the air back into outer space.

The shut-off valve 26 on the liquid side, the shut-off valve 27d on the high-pressure gas side and the shut-off valve 27s on the low-pressure gas side are valves arranged in connection holes with the external equipment and tubes (specifically, refrigerant communication tubes 6, 7d and 7s). The shut-off valve 26 on the liquid side is connected to the outdoor heat exchanger 23 via the sub-cooler 25 and the external expansion valve 38. The shut-off valve 27d on the high-pressure gas side is connected to the side of discharge of the compressor 21 through the external high pressure pipe 426. The shut-off valve 27s on the side of the low pressure gas is connected to the suction side of the compressor 21 through the external low pressure pipe 425 and the accumulator 24 The compressor 21 and the outdoor heat exchanger 23 are interconnected through the outer tube 424.

The four-way switching valve 22 switches between the state in which the discharge side of the compressor 21 is connected to the outdoor heat exchanger 23 and whose suction side is connected to the outside low pressure pipe 425 and the state in which the suction side of the compressor 21 is connected to the outdoor heat exchanger 23 and whose discharge side is connected to the external high pressure pipe 426.

The bypass tube 427 is able to connect the external high pressure tube 426 to the external low pressure tube 425. Specifically, depending on the switching state of the three-way valve 422, the external high pressure tube 426 and the tube of low external pressure 425 are interconnected through the bypass tube 427, and if this is the case, the refrigerant in the external high-pressure pipe 426 can not pass through the three-way valve 422. On the other hand, in the switching state, in which the three-way valve 422 does not connect the external high pressure pipe 426 to the outer low pressure pipe 425, the external high pressure pipe refrigerant 426 passes through the three-way valve 422 and flows into the communication pipe of the discharged gaseous refrigerant 7d through the valve closure 27d on the side of the high pressure gas, and the refrigerant in the bypass tube 427 can not pass through the three-way valve 422. As a result, communication between the external high pressure pipe 426 and the outer low pressure tube 425.

The external high pressure valve SV2b is disposed halfway to the external high pressure pipe 426. The opening and closing of the external high pressure valve SV2b allows and disconnects the coolant flow. Specifically, the external high pressure valve SV2b is provided between the four-way switching valve 22 and the three-way valve 422 in the external high-pressure pipe 426.

The outer expansion valve 38 is provided between the external heat exchanger 23 and the shut-off valve on the liquid side 26 and adjusts the amount of refrigerant that passes through it by adjusting its degree of opening.

The liquid surface sensing sensor 39 senses the amount of liquid refrigerant located upstream of the outdoor expansion valve 38 when the refrigerant is flowing in a state in which the outdoor expansion valve 38 is closed and the heat exchanger exterior 23 is functioning as a condenser. Specifically, the liquid surface sensing sensor 39 is disposed in the outdoor heat exchanger 23, and obtains data in relation to the amount of liquid refrigerant by detecting the height of the liquid surface.

In addition, several sensors are provided in the outdoor unit 402. Specifically, the outdoor unit 402 includes a suction pressure sensor (not shown) which detects the suction pressure of the compressor 21, a discharge pressure sensor (not shown) which senses the discharge pressure of the compressor 21, and a discharge temperature sensor (not shown) that senses the discharge temperature of the refrigerant on the discharge side of the compressor 21. In addition, the outdoor unit 402 includes the temperature sensor of the liquid tube 35 which senses the temperature of the liquid refrigerant flowing out of the sub-refrigerator 25. Furthermore, the outdoor unit 402 is equipped with the control unit 37 on the outside which controls the operation of components such as the frequency of the compressor 21, the switching state of the four-step switching valve 22, the speed of rotation of the motor 28m of the outdoor fan and the like. Although the illustration is omitted, the control unit 37 on the outer side is connected to each sensor, such as the detection sensor of the liquid surface 39, the motor 21m, the external fan motor 28m, the switching valve of four steps 22, the three-way valve 422, the external expansion valve 38, the sub-cooling expansion valve 472, the external high-pressure valve SV2b and the like through a communication line, and can control each from them. The control unit 37 on the outer side forms a part of the control unit 8 of the air conditioner 400, and includes a microcomputer for controlling the control unit 402, the memory 19, a receiving unit 98 receiving a signal from a remote controller, and similar. The control unit 37 on the outer side is configured in such a way that it can exchange control and similar signals with the control units 47 and 57 on the outer side of the indoor units 404 and 405.

Here, the data stored in the memory 19 includes, for example, data on the appropriate amount of refrigerant in the refrigerant circuit 410 of the air conditioner 400 in each building, which is determined taking into account the length of the tube and the like after that the 400 air conditioner has been installed in the building. As described below, the control unit 8 reads the data when performing the automatic refrigerant charge operation and the refrigerant leak detection operation in order to charge only the adequate amount of refrigerant in the refrigerant circuit 410 In addition, the memory 19 stores data on the amount of refrigerant Y determined by the liquid tube and the first quantity of refrigerant X1 collected in the external heat exchange in addition to the appropriate amount of refrigerant Z and the following ratio Z = X1 Y. Here, the amount of refrigerant Y determined by the liquid tube is the data on the amount of refrigerant when the following portions are sealed by the liquid refrigerant, whose temperature is constant in the refrigeration operation described below: once a part downstream of the outdoor heat exchanger 23 and the first refrigerant communication tube liquid 6, a portion through the liquid refrigerant communication tube 6 to the inner expansion valves 41 and 51, and a portion from a branching portion running below the outer expansion valve 38 to the expansion valve of the sub-valve. refrigerator 472 (it should be noted that the portion from the outer expansion valve 38 to the sub-refrigerator 475 is designed to have low capacity, so it has little influence on the evaluation error). In addition, the amount of refrigerant X1 collected in the external heat exchange is the amount of refrigerant that is obtained by subtracting the determined amount of refrigerant in the liquid tube Y from the appropriate amount of refrigerant Z. In addition, the memory 19 stores an expression between the liquid surface of the outdoor heat exchanger 23 and the amount of refrigerant accumulated in the portion from the outdoor expansion valve 38 to the outdoor heat exchanger 23 in the operation described below.

It should be noted that the outdoor unit is arranged with the charging tube 16 which extends to the suction side of the compressor 21 and the electromagnetic charging valve 17 which permits and closes the flow of refrigerant in the charging tube 16. The cylinder of coolant 15 must be connected to the electromagnetic load valve 17.

<Connection unit>

The connection unit 406 is installed as an assembly with the indoor unit 404, and the connection unit 407 is installed as an assembly with the indoor unit 405. Together with the liquid refrigerant communication tube 6, the refrigerant communication tube gaseous discharged 7d and gaseous refrigerant communication tube sucked 7s, connection units 406 and 407 are disposed between the indoor units 404 and 405 and the outdoor unit 402, and form a part of the refrigerant circuit 410.

Next, the connection units 406 and 407 are described. It should be noted that, since the connection unit 406 and the connection unit 407 have the same configuration, only the configuration of the connection unit 406 is described here, and with respect to the configuration of the connection unit 407, the descriptions of these respective portions are omitted.

The connection unit 406 is configured to be able to switch pipes that must be connected to its corresponding outdoor unit 404. The connection unit 406 mainly includes the liquid refrigerant communication tube 464, the gaseous refrigerant connection tube 74ds, the gaseous refrigerant communication tube 74d discharged, and the gaseous refrigerant communication tube 74s aspirated. Of these tubes, the gaseous refrigerant communication tube 74d discharged has an open / close discharge gas valve SV4d disposed halfway thereto, and the gaseous refrigerant communication tube 74s aspirated has an opening / closing valve of suction gas SV4s disposed midway of it.

The liquid refrigerant communication tube 464 corresponds to a branch portion of the liquid refrigerant communication tube 6 and is connected to the interior expansion valve 41 of the indoor unit 404

The gaseous refrigerant communication tube 74d discharged corresponds to a branching portion of the gaseous refrigerant communication tube 7d discharged, and the gaseous refrigerant communication tube 74s aspirated corresponds to a branch portion of the gaseous refrigerant communication tube 7s aspirated , and both are intended to branch out and extend to the indoor unit 404. The gaseous refrigerant 74d discharged communication tube and the gaseous refrigerant 74s communication tube aspirated are joined together through the gaseous refrigerant connection tube 74ds and are connected to the indoor heat exchanger 42.

The discharge gas opening / closing valve SV4d and the suction gas opening / closing valve SV4s, which are described below, are respectively provided for the communication of gaseous refrigerant 74d discharged and the communication tube of 74s gaseous refrigerant sucked in positions a little above the joining portion where these tubes are joined together. The SV4d discharge gas opening / closing valve and the SV4s suction gas opening / closing valve are electromagnetic valves capable of switching between a state allowing the flow of refrigerant and a state that closes the flow of refrigerant.

In addition, the connection unit 406 is equipped with a connection side control unit (not shown) that controls the operation of each portion forming the connection unit 406. Additionally, the connection side control unit includes a microcomputer for controlling the connection unit 406 and a memory, and is configured in such a way that it can exchange control signals and the like with the control unit 47 on the input side of the indoor unit 404.

As mentioned above, the configurations of the components forming the connection unit 407, the liquid refrigerant communication tube 465, the gaseous refrigerant connection tube 75ds, the gaseous refrigerant communication tube 75d discharged, the tube gaseous 75s refrigerant communication, an SV5d discharge gas opening / closing valve, an SV5s suction gas opening / closing valve, and the control unit on the connection side, are the same as the respective components described formerly forming the connection unit 406. The connection unit 407 is configured to be able to switch the tubes to be connected to its corresponding indoor unit 405.

<Operation of air conditioner>

It should be noted that the modes of operation of the air conditioner 400 in the third embodiment include: the normal mode such a simultaneous cooling and heating operation, where the control of the constituent equipment of the outdoor units 402 and 403 is carried out from according to the operational load of each of the indoor units 404 and 405; the operating mode of automatically charging the appropriate amount of refrigerant, where an adequate amount of refrigerant is charged to the refrigerant circuit 410 when a test operation is performed after installation or the like of the constituent equipment of the air conditioner 400; and the operation mode of refrigerant leak detection, where the presence of a refrigerant leak from the refrigerant circuit 410 is evaluated after said test operation has ended and normal operation has been initiated.

<Normal operation mode>

In the normal operation mode, the indoor units 404 and 405 perform the cooling operation, the heating operation, the simultaneous operation of cooling and heating, and the like. The switching between the cooling operation and the heating operation is achieved by changing a combination of opening / closing states of the discharge gas opening / closing valves SV4d and SV5d and the suction gas opening / closing valves SV4s and SV5s, which are electromagnetic valves provided in the connection unit 406. For example, when the indoor unit 404 performs the cooling operation, the discharge gas opening / closing valves SV4d are closed and the opening / closing valve is opened of suction gas SV4s. Accordingly, the liquid refrigerant which has passed through the liquid refrigerant communication tube 464 and which has been depressurized in the inner expansion valve 41 is evaporated in the indoor heat exchanger 42 which functions as an evaporator, and then passes through the gaseous refrigerant communication tube 74s sucked in place of the gaseous refrigerant communication tube 74d discharged through the gaseous refrigerant connection tube 74ds. Then, the gaseous refrigerant flows into the gaseous refrigerant communication tube 7s sucked, is sucked into the compressor 21 and is condensed in the external heat exchanger 23. The cooling operation is performed in the same way.

Furthermore, for example, when the indoor unit 404 performs the heating operation, the SV4s suction gas opening / closing valve is closed and the SV4d suction gas opening / closing valve is opened, which is opposite to the case of the refrigeration operation described above. Accordingly, the gaseous refrigerant passing through the gaseous refrigerant communication tube 74d discharged and flowing to the gaseous refrigerant connecting tube 74ds is condensed in the indoor heat exchanger 42 which functions as a condenser. Subsequently, after being depressurized by the inner expansion valve 41, the liquid refrigerant passes through the liquid refrigerant communication tube 464, flows into the liquid refrigerant communication tube 6 and evaporates in the outdoor heat exchanger 23. In addition, the evaporated gaseous refrigerant is pressurized by the compressor 21. The heating operation is carried out in this way.

As described above, the air conditioner 400 can perform the so-called simultaneous cooling and heating operation by the indoor units 404 and 405, the connection units 406 and 407, and the outdoor unit 402, where, for example, the units interiors 404 and 405 perform the cooling operation while the indoor unit performs the heating operation and the like.

Here, the refrigerant flow from when both indoor units 404 and 405 perform the cooling operation is indicated by both lines in the refrigerant circuit shown in FIG. 13. In this case, the outdoor control unit 37 of the outdoor unit 402 performs the following control: turn the motor 21m and the motor 28m of the external fan; switching the four-step switching valve 22, so that the discharged gas communicates with the external heat exchanger 23; switching the three-way valve 422 in such a manner that the outer high-pressure pipe 426 and the outer low-pressure pipe 425 do not communicate with each other; open the external expansion valve 38; adjust the opening degree of the sub-cooling expansion valve 472; and close the external high pressure valve SV2b.

The refrigerant flow of when both indoor units 404 and 405 perform the heating operation is indicated by both lines in the refrigerant circuit shown in Figure 14. In this case, the outdoor control unit 37 of the outdoor unit 402 performs the next control: turn the motor 21m and the motor 28m of the external fan; open the external high pressure valve SV2b; switching the four-step switching valve 22, in such a way that the discharged gas communicates with the external high-pressure pipe 426; switching the three-way valve 422 in such a manner that the outer high-pressure pipe 426 and the outer low-pressure pipe 425 do not communicate with each other; open the external expansion valve 38; and close the cooling expansion valve 472.

The refrigerant flow of when the indoor unit 404 performs the cooling operation and at the same time the indoor unit 405 performs the heating operation is indicated by the bold lines in the refrigerant circuit shown in figure 15. In this case, in the same way, the control unit 37 on the outer side of the outdoor unit 402 performs the following control: turn the motor 21m and the outdoor fan motor 28m; open the external high pressure valve SV2b; switching the four-step switching valve 22, in such a way that the discharged gas communicates with the external high-pressure pipe 426; switching the three-way valve 422, such that the outer high-pressure pipe 426 and the outer low-pressure pipe 425 do not communicate with each other; open the external expansion valve 38; and closing the sub-cooling expansion valve 472.

The refrigerant flow from when the outdoor unit 404 performs the heating operation and at the same time the indoor unit 405 performs the cooling operation is indicated by the bold lines in the refrigerant circuit shown in Figure 16. In this case, in the same way, the control unit 37 on the outer side of the outdoor unit 402 performs the following control: turn the motor 21m and the outdoor fan motor 28m; open the external high pressure valve SV2b; switching the four-step switching valve 22, in such a way that the discharged gas communicates with the external high-pressure pipe 426; switching the three-way valve 422, such that the outer high-pressure pipe 426 and the outer low-pressure pipe 425 do not communicate with each other; open the external expansion valve 38; and closing the sub-cooling expansion valve 472.

<Automatic loading operation mode of the proper amount of refrigerant>

In the operation of automatically charging the appropriate amount of refrigerant according to the third embodiment, as shown in Figure 17, when the receiving unit 98 receives a predetermined signal from a remote controller or the like indicating automatic charging , the refrigerant cylinder 15 is connected to the electromagnetic charging valve 17 and is adjusted to a state that communicates with the suction side of the compressor 21 through the charging tube 16 and, consequently, a state is achieved in the that the refrigerant can be charged to the refrigerant circuit 410, as in the case of the first embodiment.

Then, the control unit 8 performs the following control such that both indoor units 404 and 405 perform the cooling operation: turn the motor 21m and the motor 28m of the outdoor fan; switching the four-step valve 22, in such a way that the discharged gas communicates with the external heat exchanger 23; switching the three-way valve 422, such that the outer high-pressure pipe 426 and the outer low-pressure pipe 425 do not communicate with each other; open the external expansion valve 38; adjust the opening degree of the sub-cooling expansion valve 472; and close the valve of the external pressure SV2b. While performing such control, the control unit 8 starts to charge refrigerant from the refrigerant cylinder 15. Additionally, the control unit 8 performs constant control of the liquid temperature, while allowing the operation of automatic charging of refrigerant. .

In this constant control of the liquid temperature, the control of the condensation pressure and the control of the temperature of the liquid tube are carried out, as in the case of the first embodiment.

In the control of the condensing pressure, the flow rate of the external air supplied by the outdoor fan 28 to the outdoor heat exchanger 23 is controlled in such a way that the condensing pressure of the refrigerant in the outdoor heat exchanger 23 becomes constant . Because the condensing pressure of the refrigerant in the condenser changes greatly due to the effect of the outside temperature, the flow rate of the indoor air supplied from the outdoor fan 28 to the outdoor heat exchanger 23 is controlled by the motor 28m. Accordingly, the condensing pressure of the refrigerant in the outdoor heat exchanger 23 becomes constant, and the state will stabilize the state of the refrigerant flowing through the condenser. Accordingly, a state is achieved, in which high pressure liquid refrigerant flows in the flow path from the outdoor heat exchanger 23 to the indoor expansion valves 41 and 51, including the outdoor expansion valve 38, the side of the main refrigerant circuit of the sub-cooler 25, and the liquid refrigerant communication tube 6 and the flow path from the outdoor heat exchanger 23 to the subcooling expansion valve 472 of the subcooling circuit 474. In this manner, the pressure of the refrigerant in the portion from the outdoor heat exchanger 23 to the inner expansion valves 41 and 51 and to the sub-cooling expansion valve 472 is also stabilized and the portion is sealed by the liquid refrigerant, thus reaching a stable state. It should be noted that, in the control of the condensing pressure, the discharge pressure of the compressor 21 is used, which is detected by a discharge pressure sensor (not shown) or the temperature of the refrigerant flowing through the exchanger of external heat 23, which is detected by a heat exchange temperature sensor (not shown).

In controlling the temperature of the liquid pipe, the operation of the sub-cooler 25 is controlled in such a way that the temperature of the coolant sent from the sub-cooler 25 to the inner expansion valves 41 and 51 becomes constant. Accordingly, the density of the refrigerant in the refrigerant tubes can be stabilized from the sub-refrigerator 25 to the inner expansion valves 41 and 51, including the liquid refrigerant communication tube 6. Here, the performance of the The cooler 25 is controlled to increase or decrease the flow rate of the refrigerant flowing in the sub-cooling circuit 474, such that the temperature of the refrigerant detected by the temperature sensor of the liquid pipe 35 becomes constant. Accordingly, the amount of heat exchange between the refrigerant flowing on the side of the main refrigerant circuit of the sub-refrigerator 25 and the refrigerant flowing on the side of the sub-refrigeration circuit 474 is adjusted. that the flow rate of the refrigerant flowing in the sub-cooling circuit 474 increases or decreases as the control unit 8 adjusts the opening degree of the sub-cooling expansion valve 472.

Here, the control unit 8 evaluates whether the temperature of the liquid has met certain conditions on the basis of a value detected by the temperature sensor of the liquid tube 35.

In the third embodiment, when it is evaluated by the control unit 8 that certain conditions are met, the control unit 8 closes the expansion valves 41 and 51, the subcooling expansion valve 472, and the control valves. external expansion 38 and 88 in that order.

Accordingly, in the refrigerant circuit 410 during the cooling operation, a portion from a downstream part of the outer expansion valve 38 to the inner expansion valves 41 and 51 through the liquid refrigerant communication tube 6 and also a portion from the branching portion downstream of the outer expansion valve 38 to the sub-cooling expansion valve 472 are sealed by the liquid refrigerant (amount of refrigerant Y determined by the liquid tube), whose temperature it's constant. Then, the gaseous refrigerant is sucked into the compressor 21 from dispersed portions, where the gaseous refrigerant is present. Such as the inner tube 444, the inner heat exchanger 42, the gaseous refrigerant connecting tube 74ds, an inner tube 545, the inner heat exchanger 52, the connecting tube of gaseous refrigerant 75ds, gaseous refrigerant communication tubes 7d, 74d, and 75d discharged, gaseous refrigerant communication tubes 7s, 74s, and 75s aspirated, three-way valve 422, bypass tube 427, and tube of low outside pressure 425. Accordingly, a substantially vacuum state is created in these portions without refrigerant, and the refrigerant will accumulate as the liquid refrigerant (X1) in the outdoor heat exchanger 23.

Subsequently, as shown in Figure 18, the control unit 8 continues the cooling operation in each of the indoor units 404 and 405 and condenses and accumulates the refrigerant in the outdoor heat exchanger 23 of the outdoor unit 402 At this time, the control unit 8 evaluates whether the required amount of refrigerant (amount of refrigerant X1 collected in the external heat exchange) has accumulated or not in the outdoor heat exchanger 23, using the sensor for detecting the surface of the liquid 39. When it is judged that the required amount of refrigerant has accumulated in the outdoor heat exchanger, the control unit 8 closes the electromagnetic charging valve 17, stops the operation of the compressor 21, removes the refrigerant cylinder 15 and the automatic loading operation of the proper amount of refrigerant ends to stop the refrigerant charging from the refrigerant cylinder 15 in the refrigerant circuit 410.

<Coolant leak detection operation mode>

The operation mode for detecting refrigerant leaks is described below.

The refrigerant leak detection operation mode is substantially the same as the automatic loading operation of the proper amount of refrigerant, so that only the differences are described.

In the operation of detecting the refrigerant leakage in the third embodiment, the process of the automatic loading operation of the appropriate amount of refrigerant described above is performed, except the process of fixing the refrigerant cylinder 15 and the like, when the receiving unit 98 receives a predetermined signal from a remote controller or the like, which indicates the detection operation of the refrigerant leak.

Specifically, the control unit 8 performs the cooling operation and the constant control of the temperature of the liquid in the refrigerant circuit 410, and closes the inner expansion valves 41 and 51, the sub-cooling expansion valve 472, the outer expansion valve 38 when the liquid temperature becomes constant to determine the amount of liquid refrigerant (amount of refrigerant Y determined by the liquid tube) that fills a portion from a course below the outer expansion valve 38 to the inner expansion valves 41 and 51 through the liquid refrigerant communication tube 6 and also a portion from the branch portion downstream of the outer expansion valve 38 to the subcooling expansion valve 472. Then, continuing the cooling operation, the gaseous refrigerant is sucked into the compressor 21 from the portions s dispersed, where the gaseous refrigerant is present, such as the outer tube 444, the indoor heat exchanger 42, the gaseous refrigerant connecting tube 74ds, the inner tube 545, the indoor heat exchanger 52, the connecting tube gaseous refrigerant 75ds, gaseous refrigerant communication tubes 7d, 74d and 75d discharged, gaseous refrigerant communication tubes 7s, 74s, and 75s aspirated, three-way valve 422, bypass tube 427 and low tube external pressure 425. Accordingly, the gaseous refrigerant condenses in the outdoor heat exchanger 23 upstream of the outer expansion valve 38, resulting in the accumulation of the liquid refrigerant therein.

Here, when the height h of the liquid surface detected by the liquid surface detection sensor 39 remains the same for a predetermined period of time, the control unit 8 replaces the height h of the liquid surface at that time by an expression recorded in the memory 19 and in this way calculates the first quantity of liquid refrigerant evaluated X1 'accumulated in a potion from the outer expansion valve 38 to the outdoor heat exchanger 23.

Here, the presence of the refrigerant leak from the refrigerant circuit 10 is evaluated on the basis of whether the sum of the amount of liquid refrigerant evaluated X1 'that is calculated and the amount of refrigerant Y determined in the liquid tube is or not less than a value of the appropriate amount of refrigerant Z recorded in the memory 19. When it is smaller, the control unit 8 evaluates that there is a refrigerant leak.

It should be noted that the operation of the compressor 21 stops rapidly after the height of the surface h remains the same for a predetermined period of time and the data on the height of the liquid surface are obtained. Accordingly, the operation to detect the refrigerant leak is terminated.

(7) Characteristics of the third embodiment

In the air conditioner 400 in the third embodiment, the refrigerant circuit 410 has a complicated configuration capable of performing the cooling operation and the heating operation simultaneously. It is still possible to stop the circulation of the refrigerant by closing the outer expansion valve 38 and sucking in gaseous refrigerant which is present in dispersed portions, such as the gaseous refrigerant connection tubes 74ds and 75ds, the discharged gaseous refrigerant communication tubes 74d and 75d, the gaseous refrigerant communication tubes aspirated 74s and 75s, the gaseous refrigerant communication tube discharged 7d, the gaseous refrigerant communication tube sucked 7s, the outer high pressure tube 426, and the outer high pressure tube 425, thereby creating a substantially empty state in these portions. Additionally, the refrigerant which is present in the refrigerant circuit 410 can be accumulated in the liquid state in the following portions: the liquid refrigerant communication tubes 464, 465, and 6, a portion between the outer expansion valve 38 and the closing valve 26 on the liquid side, a portion between the outer expansion valve 38 and the subcooling expansion valve 472, and the outdoor heat exchanger 23. Accordingly, in the refrigerant circuit 410, it will be difficult for refrigerant to exist in portions other than the following: the liquid refrigerant communication tubes 464, 465, and 6, a portion between the outer expansion valve 38 and the shut-off valve 26 on the liquid side, a portion between the outer expansion valve 38 and the subcooling expansion valve 472, and the outdoor heat exchanger 23. Therefore, it is possible to evaluate the amount of refrigerant with high accuracy under simple operating conditions that only require detection of the height h by the detection sensor of the liquid surface 39 during the refrigeration operation.

(8) Alternative embodiment of the third embodiment

(TO)

The air conditioner 400 in the third embodiment described above is described as an example where only one compressor 21 is provided in the outdoor unit 402.

However, the present invention is not limited thereto. Two compressors can be provided to be connected in parallel to the outdoor unit 402.

In this case, for example, as shown in Figure 19, there is provided an air conditioner 500 having a configuration, in which a first compressor 21 and a second compressor 421 connected in parallel to the first compressor 21 are provided in the outer unit 402, and interconnections are made between the discharge side of the first compressor 21 and the discharge side of the second compressor 421 and between the intake side of the first compressor 21 and the intake side of the second compressor 421 by a bypass circuit of hot gas HPS. It should be noted that the motor 21m is provided for the first compressor 21 and a motor 421m is provided for the second compressor 421. In addition, the sensors of the discharge temperature 32 and 62 which detect the temperature of the discharge refrigerant are provided in the discharge sides of the compressors 21 and 421, respectively.

Here, the hot gas bypass circuit HPS is provided with an open / close valve SV2c and in this way it is possible to adjust the amount of refrigerant that is diverted from the discharge side to the suction side.

Additionally, the control unit 8 controls the frequencies of the motor 21m of the first compressor 21 and the motor 421m of the second compressor 421 and stops the operation of one of them, such that the first compressor 21 and the second compressor 421 will provide the Capacities required for the refrigerant circuit 410 on the basis of the values detected by the discharge temperature sensors 32, 62, and the like.

In the air conditioner 500 in the alternative embodiment (A) of the third embodiment, even if the amount of refrigerant is too high to fully condense in the outdoor heat exchanger 23 when the liquid refrigerant accumulates in the external heat exchanger 23, it is possible to adjust the balance between the condensing velocity and the delivery rate of the high pressure gaseous refrigerant by opening the opening / closing valve SV2c of the hot gas bypass circuit HPS to circulate the gaseous refrigerant again towards the vacuum of aspiration.

In addition, the discharge side and the suction side of the first compressor 21 and the discharge side and the suction side of the second compressor 421 all communicate with the hot gas bypass circuit HPS. In this way, a change in the capacities of the first compressor 21 and the second compressor 421 can be managed, such as in the case where failure on the high pressure side of the refrigerant circuit 410 can be prevented, even if the flow rate of the circulation in the refrigerant circuit 410. Accordingly, it is possible to evaluate the amount of refrigerant, while maintaining the working conditions of the first compressor 21 and the second compressor 421 as such. Therefore, even when a plurality of compressors are used, making sure that there is no non-operational compressor during the evaluation of the amount of refrigerant, it is possible to reduce an evaluation error caused by the difference between the solubility of the refrigerant in the high-temperature, high-pressure refrigerant oil in the operating compressor and the solubility of the refrigerant in the refrigerant oil at low temperature and low pressure in the non-operating compressor. Accordingly, it is possible to control a change in the amount of refrigerant dissolved in the refrigerant oil and improve the accuracy of the evaluation for the amount of refrigerant.

(B)

The air conditioner 400 in the third embodiment described above is described taking into account an example in which only an external heat exchanger 23 is provided in the outdoor unit 402. However, the present invention is not limited thereto. For example, as shown in Figure 20, an air conditioner 600 having a configuration in which the two external heat exchangers 23 and 73 are provided in the outdoor unit 402 can be provided.

Here, the air conditioner 600 according to the alternative embodiment (B), the indoor units 404 and 405 and the refrigerant communication tubes 6, 7d and 7s have the same configurations as in the third embodiment above.

As shown in Figure 20, in addition to the configuration of the third embodiment described above, the outdoor unit 402 of the air conditioner 600 according to the alternative embodiment (B) has a configuration in which an outer tube 624 is branched between the compressor 21 and the sub-cooler 475 in the refrigerant circuit 410, and heat exchanger 73, the outer expansion valve 88 and the liquid surface detection sensor 89 are provided, which are connected in parallel to the external heat exchanger 23, the outer expansion valve 38, and the sensor for detecting the liquid surface 39. In addition, the external fan 78 and the fan motor 78m are arranged to blow the outside air to the heat exchanger exterior 73.

Additionally, in addition to the data in the air conditioner 400 in the third embodiment described above, the memory 19 also stores data on the required amount of liquid refrigerant that must accumulate in a portion from the outer expansion valve 88 to the exchanger. of external heat 73 corresponding to the data on the required amount of liquid refrigerant to be accumulated in the portion from the outer expansion valve 38 to the outdoor heat exchanger 23.

Additionally, opening / closing valves 69 and 99 are provided which close the refrigerant flow in portions, respectively, between the branching portion of the outer tube 624 and the outer heat exchangers 23 and 73 arranged in a juxtaposed manner. When the required quantity of liquid refrigerant has first accumulated in one of the external heat exchangers 23 and 73, one of the open / close valves 69 and 99 is closed, that which belongs to the external heat exchanger 23 or 73 in the that the required amount of liquid refrigerant has been accumulated first. Accordingly, it is possible to introduce the liquid refrigerant only in one of the external heat exchangers 23 and 73, which has not yet been filled with the required amount of liquid refrigerant.

In the configuration described above, in the automatic loading operation mode of the appropriate amount of refrigerant and in the refrigerant leak detection operation mode, the control unit 8 first closes the outer expansion valves 38 and 88 to the Same time. Then, as the liquid refrigerant accumulates, the control unit 8 determines the level of accumulation of liquid refrigerant on the basis of each of the detection sensors of the liquid surface 39 and 89, and performs the control to close the opening / closing valves 69 and 99 according to the data stored in the memory 19 about the required quantity of liquid refrigerant in each of the external heat exchangers 23 and 73. In other words, the control unit 8 closes a of the opening / closing valves 69 and 99, that which belongs to the external heat exchanger 23 or 73 in which the required quantity of liquid refrigerant has been first accumulated, and keeps the other of the open / close valves 69 open and closed. 99 belonging to the external heat exchanger 23 or 73, in which the required quantity of liquid refrigerant has not yet been accumulated. In this state, the control unit 8 performs the control to maintain the operation,

Accordingly, the focus is placed only on the external heat exchangers 23 or 73, in which the required quantity of liquid refrigerant has not yet been accumulated, and the operation is continued until the accumulation of the liquid has been completed therein. amount required to refrigerate liquid. It should be noted that, at this moment, the liquid refrigerant can not flow back from the external heat exchanger 23 or 73, in which the required quantity of liquid refrigerant has accumulated and the opening / closing valve 69 is closed or 99, and in this way the amount of refrigerant is kept there.

It should be noted that the control unit 8 can control the opening and closing of the opening / closing valves 69 and 99 to introduce the liquid refrigerant in accordance with the ratio of the required quantity of liquid refrigerant, so that each of the external heat exchangers 23 and 73 are filled simultaneously with the required amount of liquid refrigerant, instead of performing the control to close one of the open / close valves 69 and 99, either belonging to the external heat exchanger 23 or 73 , in which the required amount of liquid refrigerant has been accumulated first. Specifically, the control unit 8 adjusts the opening / closing valve 99 to a semi-closed position when more liquid refrigerant is introduced into the outdoor heat exchanger 23, and adjusts the opening / closing valve 69 to a semi-closed position when more liquid refrigerant is introduced into the outdoor heat exchanger 73, according to the ratio based on the data stored in the memory 19 about the required amount of liquid refrigerant in the external heat exchangers 23 and 73.

(9) Another embodiment

Although the embodiments of the present invention have been described on the basis of the figures, the scope of the invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the scope of the invention. .

For example, as in an air conditioner 300 shown in Figure 11, the configuration may include a hot gas bypass 66 and a bypass valve 67 to connect the discharge side to the suction side of the compressor 21. Here, the valve bypass 67 is connected to the outdoor control unit 37 and is controlled to open and close intermittently. Accordingly, it is possible to introduce the refrigerant on the suction side of the compressor 21 through the hot gas bypass 66, and it is possible to secure at least a certain amount of the refrigerant discharged from the compressor 21.

Accordingly, when performing the operation of automatically charging the appropriate amount of refrigerant and the refrigerant leak detection operation in each embodiment described above, a problem of excessive overheating on the discharge side of the refrigerant can be avoided. compressor 21 due to a sudden drop in pressure on its suction side.

Industrial applicability

Using the present invention, the conditions required to evaluate without the amount of refrigerant is suitable or not and, therefore, it is particularly applicable to an air conditioner that evaluates the amount of refrigerant charged in a refrigerant circuit.

Claims (4)

1. - An air conditioner (1) comprising: a refrigerant circuit (10) that includes: at least one heat source unit (2) having a compressor (21) and a heat exchanger (23) on the side of the heat source, a utilization unit (4, 5) having an expansion mechanism (41, 51) on the utilization side and a heat exchanger (42, 52) on the utilization side, and a liquid refrigerant communication tube (6) and a gaseous refrigerant communication tube (7) for connecting the heat source unit to the utilization unit, the refrigerant circuit being capable of performing at least one refrigeration operation, in which the heat exchanger on the side of the heat source functions as a condenser of the refrigerant compressed in the compressor and the heat exchanger on the utilization side it functions as an evaporator of condensed refrigerant in the heat exchanger on the side of the heat source; Y a shut-off valve (26) disposed in a position that is both downstream of the heat exchanger (23) on the side of the heat source and upstream of the liquid refrigerant communication tube (6) in a direction of flow of the refrigerant in the refrigerant circuit in the refrigeration operation, and configured to be able to close the refrigerant flow: characterized in that the air conditioner comprises, in addition: a sensor for detecting the surface of the liquid (39) provided in the heat exchanger on the side of the heat source, configured to detect the quantity of liquid refrigerant accumulated in the heat exchanger on the side of the heat source, and disposed upstream of the shut-off valve (26) in the direction of refrigerant flow in the refrigerant circuit in the refrigeration operation, and configured to perform the detection of the amount of liquid refrigerant located upstream of the shut-off valve detecting a height of the liquid surface, in which the surface of the liquid is a boundary between the area where the refrigerant exists in a gaseous state and the area where the refrigerant exists in a liquid state, a memory (19 configured to store, in advance, data on the required amount of refrigerant that is required to adequately perform a conditioning operation of the air using the refrigerant circuit, and a control unit (8) configured to perform the cooling operation with the shut-off valve (26) on the basis of a detection result of the liquid surface detection sensor (39) and the required amount of refrigerant. 2. The air conditioner (1) according to claim 1, wherein the shut-off valve (26) is located at one end of the liquid refrigerant communication tube (6) and the expansion mechanism (41). , 51) on the utilization side is located at the other end of the liquid refrigerant communication tube (6), and the control unit (8) is configured to perform the control, such that the temperature of the refrigerant flow through the liquid refrigerant communication tube (6) reaches a constant value in the cooling operation and then to close the expansion mechanism (41, 51) on the utilization side and the shut-off valve (38) in that order. 3. The air conditioner (1) according to claim 1 or 2, comprising: a first heat source unit having a first compressor and a first heat exchanger of the heat source and a second heat source unit having a first compressor and a second heat exchanger of the heat source wherein: the shut-off valve includes a first shut-off valve (26) disposed downstream of the first heat exchanger of the heat source in one direction of refrigerant flow and capable of shutting off the flow of refrigerant, and a second shut-off valve (76). ) disposed downstream of the second heat exchanger of the heat source in a refrigerant flow direction and capable of closing the flow of refrigerant, The liquid surface sensing sensor includes a first refrigerant detection unit disposed upstream of the first shut-off valve in a flow direction of the refrigerant and configured to perform the detection of the amount of refrigerant existing upstream of the refrigerant. first shut-off valve in the flow direction of the refrigerant, and a second refrigerant detection unit disposed upstream of the second shut-off valve in a refrigerant flow direction and configured to perform the detection of the amount of refrigerant that exists above the second shut-off valve in the direction of refrigerant flow, the memory is configured to store, in advance, data on a first required quantity of refrigerant for the first heat source unit, and data on the second required amount of refrigerant for the second refrigerant source unit, and the control unit it is configured to control the operation of the first compressor on the basis of the first required amount of refrigerant and control of the operation of the second compressor on the basis of the second required amount of refrigerant. 4. The air conditioner (1) according to claim 3, wherein the first heat source unit includes a first re-tensioning valve (69) disposed between the first compressor and the first heat exchanger of the source of heat and set to stop the flow of refrigerant to the first compressor, and the second heat source unit includes a second check valve (99) disposed between the second compressor and the second heat source heat exchanger and configured to stop the flow of refrigerant to the second compressor.